JP2019059883A - Methacrylic resin composition - Google Patents

Abstract

To provide a methacrylic resin composition from which an oriented film having excellent optical characteristics such as birefringence and excellent qualities can be stably produced.SOLUTION: The methacrylic resin composition contains only one type of the following methacrylic resin in the composition: the methacrylic resin contains a structural unit (X) having a cyclic structure in the main chain, where the (X) structural unit is at least one unit selected from the group consisting of a structural unit derived from an N-substituted maleimide monomer and a lactone ring structural unit. The methacrylic resin composition has such characteristics that: in a temperature dispersion spectrum of a loss elasticity obtained by dynamic viscoelasticity measurement, a temperature (T) indicating a maximum in the spectrum is 120 to 160°C; and in a temperature dispersion spectrum of a loss tangent obtained by dynamic viscoelasticity measurement, a minimum of the loss tangent in the range from a temperature (T) indicating a maximum in the spectrum to a temperature higher by 50°C than the temperature is 0.70 to 1.20.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a methacrylic resin composition which has high heat resistance, is excellent in optical characteristics such as birefringence, and can stably produce a stretched film excellent in quality.

  In recent years, methacrylic resins have attracted attention as optical resins for various optical materials, for example, mainly from optical films, because they have small birefringence, which is an optical property, in addition to their excellent transparency, surface hardness, etc. , The market is expanding greatly.

  In particular, it is known that a methacrylic resin having a ring structure in its main chain and a composition containing the methacrylic resin have excellent performance in both heat resistance and optical properties, and an image display apparatus The demand is rapidly expanding in applications such as polarizer protective films or retardation films.

  Non-stretched, longitudinally uniaxially stretched, and biaxially stretched films are used as films for these image display devices, but in particular, biaxially stretched films using sequential biaxial stretching method from the viewpoint of good performance balance. There is an increase in cases where it is adopted.

  In recent years, in the case of obtaining a biaxially stretched film by continuous sequential biaxial stretching, the equipment used for the longitudinal stretching process is inexpensive because of the use of an oven type requiring a large scale heat retention furnace or heating furnace. A roll longitudinal stretching apparatus using a plurality of drive heating rolls having different circumferential speeds that can be realized is used, and then transverse stretching using a tenter is being standardized.

  However, in the case of a methacrylic resin whose heat resistance has been improved by introducing various ring structures into structural units in the methacrylic resin, the resin becomes hard and brittle, for example, when processed into a film by melt molding, etc. Only a film with poor flexibility can be obtained, breakage and cracking of the end during transport of the film, and breakage of the film itself at the time of subsequent secondary processing, etc. There are many challenges left.

  As a method for solving this problem, for example, Patent Document 1 discloses a film in which heat resistance and flexibility are compatible by performing biaxial stretching on an acrylic resin film.

  At that time, only a batch-type biaxial stretching method using a tenter is disclosed as a specific example of the biaxial stretching method, and the solution to various problems at the time of secondary stretching by continuous sequential stretching is disclosed. The contents alone do not improve enough.

  Further, in Patent Document 2, after successive biaxial stretching by combination of longitudinal stretching using rolls having different circumferential speeds and transverse stretching with a tenter, after performing longitudinal stretching under the condition that a specific birefringence characteristic is expressed, It discloses that stable biaxially oriented films can be produced by performing transverse stretching.

  As a method of developing specific birefringence characteristics, it has been proposed to control the distance between rolls different in peripheral speed to a specific interval at the time of longitudinal stretching and to use a plurality of heating means in combination.

  However, in the case where the tenter clip temperature fluctuates due to continuous operation, etc., it is insufficient, and it is not sufficient for solving the thickness fluctuation etc. in the width direction and the longitudinal direction of the obtained stretched film.

  Moreover, in patent document 3, when extending | stretching using the film before extending | stretching which consists of a thermoplastic resin which has an acrylic resin as a main component, as for the film thickness distribution of the width direction of the film before extending | stretching, an edge part becomes thicker. It is disclosed that stable stretching is possible by controlling.

  Looking at the evaluation results regarding the improvement effect of stretchability, simple two-stage evaluation results of "cracked edge" or "no problem" are disclosed.

  However, since it is important to form a specific thickness distribution in the width direction in the film before stretching, a special T-die is required, or in order to stably obtain a film having a specific thickness distribution, Not only complicated operations are required, for example, high control is required when discharging the resin, but in longitudinal stretching using the roll stretching method thereafter, the variation of the stretching point at the time of stretching and the width of the film after stretching There is a concern about thickness variations in the direction or the longitudinal direction.

  Furthermore, in Patent Document 4, when longitudinally stretching a film made of a thermoplastic resin containing an acrylic polymer, the roll temperature and the roll temperature are measured using a roll drawing apparatus including a plurality of preheating rolls and a plurality of cooling rolls in its configuration. It is disclosed that stable longitudinal stretching can be achieved by adopting a method of heating the near infrared radiation having a specific wavelength in the stretching section and using an infrared radiation section capable of emitting near infrared radiation while controlling the speed of the ing.

  However, in Patent Document 4, it is premised to use an unstretched film having a specific film thickness distribution disclosed in Patent Document 3, and it is effective even when it does not have a specific film thickness distribution. I'm not sure. Further, the evaluation criteria of the stretching stability are also not disclosed specifically, and in longitudinal stretching by roll stretching, the shift of the stretching point and the variation of the film width accompanying it, the thickness in the width direction or the longitudinal direction of the film With regard to the resolution, as well as the resolution of defects such as film edge curling, it remains unclear whether the disclosure alone can solve it.

  In the patent documents shown above, it is an attempt to solve a subject mainly by the film characteristic at the time of film stretching, and the device of a film stretching apparatus, and stretching conditions.

  On the other hand, in Patent Document 5, as the film for stretching, a film made of different thermoplastic resins at the end and the center is used, and as a resin constituting the end, a thermoplastic resin having higher impact strength is used. It is disclosed that by adopting, the film can be stretched stably.

  However, it is necessary to use an expensive T-die having a structure in which the flow path is controlled by using different thermoplastic resins, and further, when the film is formed, thickness unevenness may increase or a phase between thermoplastic resins used. When the solubility is insufficient, there are many problems such as the film being easily broken during film formation, which is not practical.

  Furthermore, in Patent Document 6, in order to cope with further thinning of the stretched film, the motion of the thermoplastic resin used in the stretching of the thermoplastic resin containing an amorphous vinyl polymer having a ring structure in the main chain It is disclosed that a thin film biaxially stretched film having a thickness of 35 μm or less can be produced by controlling the molecular weight between entanglement points in the rubbery flat region of the target visco-elasticity spectrum and the entanglement number within a specific range.

  In general, when a methacrylic resin is used as the non-crystalline vinyl polymer, the rubbery flat region in the dynamic viscoelastic spectrum is often not clearly appeared in many cases, and in particular, the methacryl having a relatively high glass transition temperature. In the case of a system resin, it is often not possible to accurately determine parameters related to entanglement by dynamic viscoelasticity spectra.

  Although Patent Document 6 adopts a parameter related to entanglement as the characteristic of the thermoplastic resin to be used, the disclosed example in the embodiment entangles using the viscoelastic property of the unstretched film after melt film formation. There are also many unclear points regarding the decision, such as calculating the parameter concerning.

  In addition, as a specific example of the biaxial stretching method, only an example in which a thin film can be obtained by the batch-type biaxial stretching method using a tenter is disclosed, and various problems in continuous sequential stretching including roll stretching and tenter stretching There is no mention or suggestion as to whether it can be solved.

JP, 2008-242426, A JP, 2010-271690, A JP, 2010-69731, A JP, 2014-83703, A JP, 2014-69437, A JP, 2014-193982, A

  In recent years, with the increase in the area of image display devices, thin film formation and increase in the area of these films have been strongly demanded, and in addition to the solution of the problems by devising film drawing devices and drawing conditions, the resin or resin composition itself Of a methacrylic resin having excellent optical properties and heat resistance, and a composition containing the same, which can solve the problems described above, solve the above-mentioned problems at an early stage, and have excellent molding process stability and high quality optical film. It is expected to be provided.

  Then, an object of this invention is to provide the methacrylic resin composition which is excellent in optical characteristics, such as a birefringence, and can manufacture stably the stretched film excellent in the grade.

  The present inventors conducted intensive studies to solve the above-mentioned problems, and as a result, when the film before stretching is prepared into a stretched film through a stretching step, a methacrylic resin having a ring structure in the main chain Is subjected to various thermal histories within a temperature range from about 100 ° C. lower than the glass transition temperature to about 50 ° C. higher than the glass transition temperature, and further, in this temperature range, the main chain It was noted that the methacrylic resin having a ring structure was subjected to stretching while changing its higher-order structure from the glassy state to the rubbery state before the start of melt flow.

  As a result of further intensive investigations, the inventors of the present invention have measured dynamic viscoelasticity observed in the above-mentioned temperature range in order to stably produce a stretched film having stable quality and high optical properties. A methacrylic resin and / or a composition thereof in which the higher order structure of the solid in the temperature region showing the maximum value of the loss elastic modulus and the maximum value of the loss tangent obtained and the temperature region around that are controlled as a starting material It has been found that the above problems can be solved by using the present invention, and the present invention has been completed.

That is, the present invention is as follows.
[1] At least at least one selected from the group consisting of a structural unit (X) having a ring structure in the main chain, and the (X) structural unit is a structural unit derived from an N-substituted maleimide monomer, and a lactone ring structural unit It is a methacrylic resin composition containing only one kind of methacrylic resin in its composition, and the temperature (T _{G ′ ′ max} ) at which the maximum value is obtained in the temperature dispersion spectrum of the loss elastic modulus determined by dynamic viscoelasticity measurement Of the loss tangent in the range from a temperature (T _{tan δmax} ) at which the temperature is 120 to 160 ° C. and the maximum value is shown in the temperature dispersion spectrum of the loss tangent determined by dynamic viscoelasticity measurement to a temperature 50 ° C. higher than the temperature It is 0.70 to 1.20, The methacrylic resin composition characterized by the above-mentioned.
[2] In the range from the temperature (T _{tan δmax} ) at which the maximum value is shown in the temperature dispersion spectrum of the loss tangent to the temperature 50 ° C. higher than the temperature, the loss tangent is 10% higher than the minimum value of the loss tangent The methacrylic resin composition as described in [1] whose temperature difference ((DELTA) T) which shows to a value is 12-24 degreeC.
[3] The methacrylic resin composition according to [1] or [2], wherein the weight average molecular weight (Mw) in terms of polymethyl methacrylate measured by GPC is 120,000 to 260,000.
[4] The (X) structural unit contains a structural unit derived from an N-substituted maleimide monomer, and the content of the structural unit derived from the N-substituted maleimide monomer is 100% by mass of the methacrylic resin The methacrylic resin composition according to any one of [1] to [3], which is 5 to 40% by mass.
[5] The above (X) structural unit contains a lactone ring structural unit, and the content of the lactone ring structural unit is 5 to 40% by mass, based on 100% by mass of the methacrylic resin. The methacrylic resin composition according to any one of [3].
[6] The methacrylic resin composition according to any one of [1] to [5], wherein the absolute value of the photoelastic coefficient is 2.0 × 10 ⁻¹² Pa ⁻¹ or less.
[7] The methacrylic resin composition according to [6], wherein the absolute value of the photoelastic coefficient is 1.0 × 10 ⁻¹² Pa ⁻¹ or less.

  According to the present invention, it is possible to provide a methacrylic resin composition capable of stably producing a stretched film excellent in optical properties such as birefringence and excellent in quality.

It is a figure which shows the temperature dispersion spectrum of a representative loss elastic modulus, and the temperature dispersion spectrum of loss tangent which are obtained when using the methacrylic resin composition of this embodiment for a dynamic-viscoelasticity measurement. In the figure, particularly on the vertical axis, the vertical axis on the right represents loss tangent (−), and the vertical axis on the left represents loss elastic modulus (Pa).

  Hereinafter, a mode for carrying out the present invention (hereinafter referred to as “the present embodiment”) will be described in detail, but the present invention is not limited to the following description, and within the scope of the gist thereof Various modifications are possible.

(Methacrylic resin composition)
The methacrylic resin composition of the present embodiment contains a methacrylic resin, and optionally contains other thermoplastic resin and an additive.

-Methacrylic resin-
The methacrylic resin in the present embodiment contains a structural unit (X) having in the main chain at least one ring structure selected from the group consisting of a structural unit derived from an N-substituted maleimide monomer, and a lactone ring structural unit. It also contains an acid ester monomer unit.

  Hereinafter, each monomer structural unit is demonstrated.

--Methacrylic acid ester monomer unit--
First, the methacrylic acid ester unit will be described.
The methacrylic acid ester monomer unit is formed, for example, from a monomer selected from methacrylic acid esters shown below. Examples of methacrylic acid esters include methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, isopropyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, t-butyl methacrylate, 2-ethylhexyl methacrylate, and methacrylic acid. Cyclopentyl, cyclohexyl methacrylate, cyclooctyl methacrylate, tricyclodecyl methacrylate, dicyclooctyl methacrylate, tricyclododecyl methacrylate, isobornyl methacrylate, phenyl methacrylate, benzyl methacrylate, 1-phenylethyl methacrylate, methacrylic acid 2-phenoxyethyl, 3-phenylpropyl methacrylate, 2,4,6-tribromophenyl methacrylate and the like can be mentioned.
These monomers may be used alone or in combination of two or more.
Among the above-mentioned methacrylic acid esters, methyl methacrylate and benzyl methacrylate are preferable in that the transparency and weather resistance of the resulting methacrylic resin are excellent.
The methacrylic acid ester unit may contain only one kind or two or more kinds.

  The structural unit (X) in the methacrylic resin containing the structural unit (X) having a ring structure in the main chain is particularly described below.

--Structural unit derived from N-substituted maleimide monomer--
Next, structural units derived from N-substituted maleimide monomers are described.
The structural unit derived from the N-substituted maleimide monomer may be at least one selected from a monomer represented by the following formula (1) and / or a monomer represented by the following formula (2), Preferably, it is formed from both of the monomers represented by the following formula (1) and the following formula (2).

式（１）中、Ｒ^１は、炭素数７〜１４のアリールアルキル基、炭素数６〜１４のアリール基のいずれかを示し、Ｒ^２及びＲ^３は、それぞれ独立に、水素原子、炭素数１〜１２のアルキル基、炭素数６〜１４のアリール基のいずれかを示す。
また、Ｒ^２がアリール基の場合には、Ｒ^２は、置換基としてハロゲンを含んでいてもよい。
また、Ｒ^１は、ハロゲン原子、炭素数１〜６のアルキル基、炭素数１〜６のアルコキシ基、ニトロ基、ベンジル基等の置換基で置換されていてもよい。

In formula (1), R ¹ represents any of an arylalkyl group having 7 to 14 carbon atoms and an aryl group having 6 to 14 carbon atoms, and R ² and R ³ each independently represent a hydrogen atom or a carbon number It shows any of a 1 to 12 alkyl group and an aryl group having 6 to 14 carbon atoms.
When R ² is an aryl group, R ² may contain halogen as a substituent.
In addition, R ¹ may be substituted with a substituent such as a halogen atom, an alkyl group having 1 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, a nitro group, or a benzyl group.

式（２）中、Ｒ^４は、水素原子、炭素数３〜１２のシクロアルキル基、炭素数１〜１８のアルキル基のいずれかを示し、Ｒ^５及びＲ^６は、それぞれ独立に、水素原子、炭素数１〜１２のアルキル基、炭素数６〜１４のアリール基のいずれかを示す。

In formula (2), R ⁴ represents a hydrogen atom, a cycloalkyl group having 3 to 12 carbon atoms, or an alkyl group having 1 to 18 carbon atoms, and R ⁵ and R ⁶ each independently represent a hydrogen atom And any of an alkyl group having 1 to 12 carbon atoms and an aryl group having 6 to 14 carbon atoms.

Specific examples are shown below.
Examples of the monomer represented by the formula (1) include N-phenylmaleimide, N-benzylmaleimide, N- (2-chlorophenyl) maleimide, N- (4-chlorophenyl) maleimide, and N- (4-bromo). Phenyl) maleimide, N- (2-methylphenyl) maleimide, N- (2-ethylphenyl) maleimide, N- (2-methoxyphenyl) maleimide, N- (2-nitrophenyl) maleimide, N- (2, 4 , 6-trimethylphenyl) maleimide, N- (4-benzylphenyl) maleimide, N- (2, 4, 6- tribromophenyl) maleimide, N-naphthyl maleimide, N- anthracenyl maleimide, 3-methyl-1 -Phenyl-1H-pyrrole-2,5-dione, 3,4-dimethyl-1-phenyl-1H-pyrrole-2,5- One, 1,3-diphenyl -1H- pyrrole-2,5-dione, 1,3,4-triphenyl -1H- pyrrole-2,5-dione, and the like.
Among these monomers, N-phenyl maleimide and N-benzyl maleimide are preferable from the viewpoint of excellent heat resistance of the resulting methacrylic resin and optical properties such as birefringence.
These monomers may be used alone or in combination of two or more.

Examples of the monomer represented by the formula (2) include N-methyl maleimide, N-ethyl maleimide, N-n-propyl maleimide, N-isopropyl maleimide, N-n-butyl maleimide, N-isobutyl maleimide, N-s-butyl maleimide, N-t-butyl maleimide, N-n-pentyl maleimide, N-n-hexyl maleimide, N-n-heptyl maleimide, N-n-octyl maleimide, N-lauryl maleimide, N-stearyl Maleimide, N-cyclopentylmaleimide, N-cyclohexylmaleimide, 1-cyclohexyl-3-methyl-1H-pyrrole-2,5-dione, 1-cyclohexyl-3,4-dimethyl-1H-pyrrole-2,5-dione, 1-Cyclohexyl-3-phenyl-1H-pyrrole-2,5-dione And 1-cyclohexyl-3,4-diphenyl -1H- pyrrole-2,5-dione can be cited.
Among these monomers, N-methyl maleimide, N-ethyl maleimide, N-isopropyl maleimide, and N-cyclohexyl maleimide are preferable from the viewpoint that the weather resistance of the methacrylic resin is excellent, and low as recently required for optical materials N-cyclohexyl maleimide is particularly preferable because of its excellent hygroscopicity.
These monomers may be used alone or in combination of two or more.

In the methacrylic resin of the present embodiment, the combined use of the monomer represented by the formula (1) and the monomer represented by the formula (2) provides highly controlled birefringence characteristics. Particularly preferred is the ability to be expressed.
The molar ratio of the content (B1) of the structural unit derived from the monomer represented by the formula (1) to the content (B2) of the structural unit derived from the monomer represented by the formula (2), (B1 / B2) is preferably more than 0 and 15 or less, more preferably more than 0 and 10 or less. When the molar ratio (B1 / B2) is in this range, the methacrylic resin of the present embodiment maintains transparency, is not accompanied by yellowing, and has good heat resistance and good without impairing the environmental resistance. Express photoelastic properties.

The content of the structural unit derived from the N-substituted maleimide monomer is not particularly limited as long as the composition to be obtained satisfies the range of the glass transition temperature of the present embodiment, but 100% by mass of a methacrylic resin Preferably, it is 5 to 40% by mass, more preferably 5 to 35% by mass.
When it is in this range, the methacrylic resin can obtain a more sufficient heat resistance improvement effect, and further, a more preferable improvement effect can be obtained with respect to the weather resistance, the low water absorption and the optical properties. When the content of the structural unit derived from the N-substituted maleimide monomer is 40% by mass or less, the reactivity of the monomer component decreases during the polymerization reaction, and the amount of unreacted monomer remains large. It is effective to prevent the physical properties of the methacrylic resin from being lowered due to

The methacrylic resin having a structural unit derived from the N-substituted maleimide monomer in the present embodiment can be copolymerized with the methacrylic acid ester monomer and the N-substituted maleimide monomer within the range not impairing the object of the present invention. May contain structural units derived from other monomers.
For example, as another copolymerizable monomer, aromatic vinyl; unsaturated nitrile; acrylic acid ester having cyclohexyl group, benzyl group or alkyl group having 1 to 18 carbon atoms; glycidyl compound; unsaturated carboxylic acid Etc. can be mentioned.
Examples of the aromatic vinyl include styrene, α-methylstyrene, divinylbenzene and the like.
Examples of the unsaturated nitrile include acrylonitrile, methacrylonitrile, ethacrylonitrile and the like.
Moreover, methyl acrylate, an ethyl acrylate, a propyl acrylate, an isopropyl acrylate, a butyl acrylate etc. are mentioned as said acrylic ester.
Moreover, as a glycidyl compound, glycidyl acrylate, allyl glycidyl ether, etc. are mentioned.
Examples of unsaturated carboxylic acids include acrylic acid, methacrylic acid, itaconic acid, maleic acid, fumaric acid, and their half esters or anhydrides.
The structural units derived from the other copolymerizable monomers may have only one kind or two or more kinds.

The content of structural units derived from these other copolymerizable monomers is preferably 0 to 20% by mass, preferably 0.1 to 15% by mass, based on 100% by mass of the methacrylic resin. Is more preferable, and 0.1 to 10% by mass is more preferable.
When the content of structural units derived from other monomers is in this range, it is preferable because the molding processability and mechanical properties of the resin can be improved without impairing the original effect of introducing a ring structure into the main chain.

As a method for producing a methacrylic resin having a structural unit derived from an N-substituted maleimide monomer in the main chain, it is preferable to polymerize the monomer by radical polymerization in a solvent using a so-called solution polymerization method.
In the solution polymerization in this embodiment, as the polymerization type, polymerization temperature, monomer concentration, addition amount of polymerization initiator, addition speed, addition timing, addition amount of chain transfer agent, addition speed, addition timing during polymerization. Batch polymerization methods and semi-batch polymerization methods can be preferably used, and polymerization conditions such as the type and concentration of the solvent used can be arbitrarily changed.
By adopting this method, resins and resin compositions satisfying the controlled solid dynamic viscoelastic properties of the present invention tend to be more easily prepared, which is preferable.

  Hereinafter, as an example of a method for producing a methacrylic resin having a structural unit derived from an N-substituted maleimide monomer (hereinafter sometimes referred to as "maleimide copolymer"), it is produced by radical polymerization using a solution polymerization method. The specific case will be described.

The polymerization solvent used for the solution polymerization is not particularly limited as long as it can increase the solubility of the maleimide copolymer obtained by the polymerization and appropriately maintain the viscosity of the reaction solution for the purpose of preventing gelation and the like.
Specific polymerization solvents include, for example, aromatic hydrocarbons such as toluene, xylene, ethylbenzene and isopropylbenzene; ketones such as methyl isobutyl ketone, butyl cellosolve, methyl ethyl ketone and cyclohexanone; polar solvents such as dimethylformamide and 2-methylpyrrolidone It can be used.
These may be used alone or in combination of two or more.

In the present embodiment, a method of additionally adding a polymerization solvent having different chain transfer ability during polymerization can also be preferably used for the purpose of obtaining a resin having controlled solid dynamic viscoelasticity characteristics.
Generally, in radical polymerization in solution, it is known that the degree of chain transfer reaction varies greatly depending on the type of solvent used (for example, Kodansha Publishing: Synthesis of Polymers (top), Reference to First Radical Polymerization) ).
In practice, it differs depending on each reaction condition, so it needs to be confirmed in the system actually used, but from the study results of the present inventors, (for example, from immediately after the start of addition of the polymerization initiator During any time up to the time, a solvent such as methyl isobutyl ketone with relatively low chain transfer ability is used, and during the polymerization (eg, after the start of the addition of the polymerization initiator from the start of addition of the polymerization initiator) Can be exemplified by the method of additionally adding a solvent such as toluene, xylene, ethylbenzene having a relatively large chain transfer ability.

  In addition, an alcohol such as methanol, ethanol or isopropanol may be used in combination as a polymerization solvent as long as the dissolution of the polymerization product during polymerization is not inhibited.

  The amount of the solvent at the time of polymerization is not particularly limited as long as the polymerization proceeds, precipitation of the copolymer and the monomer used does not occur at the time of production, and the like, and can be easily removed. It is preferable to set it as 10-100 mass parts, when the total amount of is made into 100 mass parts. The amount is more preferably 25 to 100 parts by mass, further preferably 40 to 100 parts by mass, and still more preferably 50 to 100 parts by mass.

In the present embodiment, in order to obtain a resin having a controlled solid dynamic viscoelasticity property, 100 parts by mass when the total amount of monomers to be blended is 100 parts by mass in the amount of solvent at the time of polymerization. A method in which polymerization is carried out while appropriately changing the solvent concentration during polymerization while keeping the following range can be preferably used.
More specifically, for example, the polymerization solvent to be used is 100 parts by mass, and 40 to 60 parts by mass of the polymerization solvent is blended before the start of the polymerization, and during polymerization (for example, 6 hours from immediately after addition of the polymerization initiator) While the remaining 60 to 40 parts by mass may be blended. Furthermore, finally, when the total amount of monomers to be blended in the polymerization solution is 100 parts by mass, the solvent amount of the polymerization solvent is 100 parts by mass or less, more preferably 95 parts by mass or less And the like can be exemplified.
By adopting this method, it is possible to continuously change the molecular weight of the formed polymer by changing the concentration of the solvent having chain transfer ability during the polymerization, thereby controlling the dynamic viscoelasticity of the controlled solid. It is preferable because it tends to be easy to prepare a resin and a resin composition having characteristics, and it is possible to stably manufacture a stretched film excellent in stretchability and excellent in grade.

  The polymerization temperature is not particularly limited as long as polymerization proceeds, but from the viewpoint of productivity, it is preferably 50 to 200 ° C., more preferably 80 to 200 ° C. The temperature is more preferably 90 to 150 ° C, still more preferably 100 to 140 ° C, and still more preferably 100 to 130 ° C.

In the present embodiment, in order to obtain a resin having controlled solid dynamic viscoelastic properties, a method of changing the polymerization temperature at an appropriate stage during the polymerization can be preferably used.
More specifically, in the initial stage of polymerization (for example, up to 1 hour from the start of addition of the polymerization initiator), select a lower polymerization temperature within the above temperature range, and during the polymerization (for example, from the start of addition of the polymerization initiator) A method of changing the polymerization temperature to a higher temperature within the above temperature range and continuing the polymerization after 1 hour can be exemplified. The difference between the higher polymerization temperature and the lower polymerization temperature is preferably 10 to 30 ° C., more preferably 10 to 20 ° C.
By adopting this method, a resin and resin composition having controlled solid dynamic viscoelasticity tend to be easily prepared, and a stretched film excellent in stretchability and quality is stably produced. It is preferable because a resin and a resin composition that can be obtained can be obtained.

  Further, the polymerization time is not particularly limited as long as the necessary degree of polymerization can be obtained at the required conversion rate, but it is 0.5 to 10 hours from the viewpoint of productivity etc. Preferably, it is 1 to 8 hours more preferably.

  At the time of the polymerization reaction, polymerization may be carried out by adding a polymerization initiator or a chain transfer agent, if necessary.

As the polymerization initiator, any initiator generally used in radical polymerization can be used. For example, cumene hydroperoxide, diisopropylbenzene hydroperoxide, di-t-butyl peroxide, lauroyl peroxide, benzoylperoxide Organic peroxides such as oxides, t-butyl peroxyisopropyl carbonate, t-amyl peroxy-2-ethylhexanoate, t-amyl peroxy isononanoate, 1,1-di-t-butylperoxycyclohexane and the like; 2,2'-azobis (isobutyronitrile), 1,1'-azobis (cyclohexanecarbonitrile), 2,2'-azobis (2,4-dimethylvaleronitrile), dimethyl-2,2'-azobis Azo compounds such as isobutyrate; it can.
These may be used alone or in combination of two or more.
The addition amount of the polymerization initiator may be 0.01 to 1 part by mass, preferably 0.05 to 0.5 parts by mass, when the total amount of monomers used for polymerization is 100 parts by mass. is there.

These polymerization initiators may be added at any stage as long as the polymerization reaction is in progress.
In the present embodiment, the type of initiator, the amount of initiator, the polymerization temperature, etc., so that the ratio of the total amount of radicals generated from the polymerization initiator to the total amount of unreacted monomers remaining in the reaction system is always below a certain value. It is preferable to select as appropriate.
In particular, in this embodiment, the addition amount per unit time of the polymerization initiator per unit time at least once in the first half of the time from the start of the addition of the polymerization initiator to the end of the addition (polymerization initiator addition time) It is preferable to make it smaller than the addition amount per time.
By employing this method, it is possible to suppress the amount of oligomers or low molecular weight products formed in the late stage of polymerization, or to suppress the overheating during polymerization to achieve the stability of polymerization.

As a chain transfer agent, a chain transfer agent used in general radical polymerization can be used. For example, n-butyl mercaptan, n-octyl mercaptan, n-decyl mercaptan, n-dodecyl mercaptan, 2-ethylhexyl thioglycolate, etc. Mercaptan compounds; halogen compounds such as carbon tetrachloride, methylene chloride and bromoform; unsaturated hydrocarbon compounds such as α-methylstyrene dimer, α-terpinene, dipentene and terpinolene; and the like.
These may be used alone or in combination of two or more.
These chain transfer agents may be added at any stage as long as the polymerization reaction is in progress, and is not particularly limited.
The addition amount of the chain transfer agent may be 0.01 to 1 part by mass, preferably 0.05 to 0.5 parts by mass, when the total amount of the monomers used for polymerization is 100 parts by mass.

In this embodiment, a chain transfer agent is added at the initial stage of polymerization (for example, 1 to 2.5 hours after the start of addition of the polymerization initiator) in order to obtain a resin having controlled solid dynamic viscoelasticity characteristics. It is also possible to preferably use a method in which a chain transfer agent is additionally added when polymerization conversion reaches a range not exceeding 60% after polymerization initiation. In addition, as a timing of said additional addition, it is preferable to set it as the time of the range of 20-55% of a polymerization conversion ratio, More preferably, it is the time of the range of 20-50%.
The polymerization conversion rate in the present embodiment means that a part of the polymerization solution is collected, dissolved in chloroform, and the amount of monomer remaining in the polymerization solution is single monomer remaining in the sample using gas chromatography. The body concentration was measured to determine the total mass (a) of the monomers remaining in the polymerization solution. And it says the value calculated | required by calculation formula (ba) / bx100 from this gross mass (a) and the gross mass (b) of the monomer added by the time of extract | collecting a sample.
When a chain transfer agent is added with a polymerization conversion exceeding 60%, the low molecular weight component tends to increase more, and the resin and resin composition having controlled solid dynamic viscoelasticity characteristics of the present invention Is not likely to be obtained.
By adopting this method, a resin and resin composition having controlled solid dynamic viscoelasticity tend to be easily prepared, and a stretched film excellent in stretchability and quality is stably produced. It is preferable because a resin and resin composition that can be obtained can be obtained.

  In solution polymerization, it is important to reduce the dissolved oxygen concentration in the polymerization solution as much as possible. For example, the dissolved oxygen concentration is preferably 10 ppm or less. The dissolved oxygen concentration can be measured, for example, using a dissolved oxygen meter DO meter B-505 (manufactured by Iijima Electronics Co., Ltd.). As a method of reducing the concentration of dissolved oxygen, a method of bubbling an inert gas into the polymerization solution, an operation of pressurizing the inside of a container containing the polymerization solution to about 0.2 MPa with inert gas before polymerization and repeating the operation of releasing pressure are repeated. A method such as a method of passing an inert gas into a container containing a polymerization solution can be appropriately selected.

  The method for recovering the polymer from the polymerization solution obtained by solution polymerization is not particularly limited, but, for example, poor solvents such as hydrocarbon solvents and alcohol solvents which do not dissolve the polymerization product obtained by polymerization The polymerization liquid is added in the presence of an excess amount, and then the treatment (emulsification and dispersion) is performed by a homogenizer, and the unreacted monomer is subjected to pretreatment such as liquid-liquid extraction and solid-liquid extraction, Alternatively, a method of separating from the polymerization solution; or a method of separating a polymerization solvent or an unreacted monomer via a process called a degassing step; and recovering a polymerization product;

Here, the volatilization step refers to a step of removing volatile components such as a polymerization solvent, residual monomers, reaction byproducts, etc. under heating and reduced pressure conditions.
As an apparatus used for the volatilization process, for example, a degassing apparatus comprising a tubular heat exchanger and a degassing tank; thin film evaporators such as Weibren manufactured by Shinko Environmental Solutions Co., Ltd., Exeva, Contra manufactured by Hitachi, Inc. Examples thereof include a vented extruder having a residence time and a surface area sufficient to exert the degassing performance.
A degassing step using a degassing apparatus in which any two or more of these devices are combined can also be used.

The processing temperature in the devolatilizer is preferably 150 to 350 ° C, more preferably 170 to 300 ° C, and still more preferably 200 to 280 ° C. When the temperature is 150 ° C. or more, it is effective to prevent the residual volatile matter from increasing. On the other hand, when the temperature is 350 ° C. or less, there is little possibility that coloring or decomposition of the obtained methacrylic resin will occur.
The degree of vacuum in the volatilization apparatus may be in the range of 10 to 500 Torr, preferably in the range of 10 to 300 Torr. If the degree of vacuum is 500 Torr or less, volatile components tend not to remain, and if the degree of vacuum is 10 Torr or more, industrial implementation is easier.
The treatment time is appropriately selected depending on the amount of residual volatile component, but in order to suppress the coloring and decomposition of the obtained methacrylic resin, the shorter, the better.

  The polymer recovered through the volatilization process is processed into pellets in a process called a granulation process.

In the granulation step, the molten resin is extruded into a strand from the porous die and processed into a pellet by a cold cut method, an airborne hot cut method, an underwater strand cut method, and an under water cut method.
In addition, when the extruder with a vent is employ | adopted as a devolatilization apparatus, you may combine a devolatilization process and a granulation process.

-Lactone ring structural unit--
The methacrylic resin having a lactone ring structural unit in its main chain is, for example, disclosed in JP-A-2001-151814, JP-A-2004-168882, JP-A-2005-146084, JP-A-2006-96960, JP-A-2006-96960. They can be formed by the methods described in JP-A-2006-171464, JP-A-2007-63541, JP-A-2007-297620, JP-A-2010-180305, and the like.

  The lactone ring structural unit constituting the methacrylic resin of the present embodiment may be formed after resin polymerization.

The lactone ring structural unit in the present embodiment is preferably a six-membered ring because of excellent stability of the ring structure.
As a lactone ring structural unit which is a six-membered ring, for example, a structure represented by the following general formula (4) is particularly preferable.

上記一般式（４）において、Ｒ^１０、Ｒ^１１及びＲ^１２は、互いに独立して、水素原子、又は炭素数１〜２０の有機残基である。
有機残基としては、例えば、メチル基、エチル基、プロピル基等の炭素数１〜２０の飽和脂肪族炭化水素基（アルキル基等）；エテニル基、プロペニル基等の炭素数２〜２０の不飽和脂肪族炭化水素基（アルケニル基等）；フェニル基、ナフチル基等の炭素数６〜２０の芳香族炭化水素基（アリール基等）；これら飽和脂肪族炭化水素基、不飽和脂肪族炭化水素基、芳香族炭化水素基における水素原子の一つ以上が、ヒドロキシ基、カルボキシル基、エーテル基、エステル基からなる群から選ばれる少なくとも１種の基により置換された基；等が挙げられる。

In the above general formula (4), R ¹⁰ , R ¹¹ and R ¹² are each independently a hydrogen atom or an organic residue having 1 to 20 carbon atoms.
Examples of the organic residue include saturated aliphatic hydrocarbon groups having 1 to 20 carbon atoms such as methyl, ethyl and propyl (such as alkyl groups); and non-C 2 to 20 carbons such as ethenyl and propenyl. Saturated aliphatic hydrocarbon group (alkenyl group, etc.); C6-20 aromatic hydrocarbon group such as phenyl group, naphthyl group etc. (aryl group etc.); these saturated aliphatic hydrocarbon groups, unsaturated aliphatic hydrocarbon And groups in which at least one hydrogen atom in the group or aromatic hydrocarbon group is substituted with at least one group selected from the group consisting of a hydroxy group, a carboxyl group, an ether group, and an ester group; and the like.

  The lactone ring structure is obtained, for example, by copolymerizing an acrylic acid-based monomer having a hydroxy group with a methacrylic acid ester monomer such as methyl methacrylate to form a hydroxy group and an ester group or a carboxyl group in a molecular chain. After introduction, it can be formed by causing dealcoholization (esterification) or dehydration condensation (hereinafter also referred to as “cyclization condensation reaction”) between these hydroxy group and ester group or carboxyl group.

  Examples of acrylic acid monomers having a hydroxy group used for polymerization include 2- (hydroxymethyl) acrylic acid, 2- (hydroxyethyl) acrylic acid, and alkyl 2- (hydroxymethyl) acrylate (for example, 2- (hydroxymethyl) acrylic acid). Methyl (hydroxymethyl) acrylate, ethyl 2- (hydroxymethyl) acrylate, isopropyl 2- (hydroxymethyl) acrylate, n-butyl 2- (hydroxymethyl) acrylate, t- 2- (hydroxymethyl) acrylate Butyl), alkyl 2- (hydroxyethyl) acrylate and the like, preferably 2- (hydroxymethyl) acrylic acid and alkyl 2- (hydroxymethyl) acrylate which are monomers having a hydroxyallyl moiety. , Particularly preferably methyl 2- (hydroxymethyl) acrylate 2- (hydroxymethyl) acrylate.

The content of the lactone ring structural unit in the methacrylic resin having a lactone ring structural unit in the main chain is not particularly limited as long as it satisfies the range of the glass transition temperature preferable as the composition of the present embodiment, but the methacrylic resin It is preferable that it is 5-40 mass% with respect to 100 mass%, More preferably, it is the range of 5-35 mass%.
When the content of the lactone ring structural unit is within this range, ring structure introduction effects such as solvent resistance improvement and surface hardness improvement can be exhibited while maintaining molding processability.
In addition, the content rate of the lactone ring structure in methacrylic resin can be determined using the method of the above-mentioned and patent document description.

Even if the methacrylic resin having a lactone ring structural unit has a structural unit derived from another monomer copolymerizable with the above-described methacrylic acid ester monomer and an acrylic acid monomer having a hydroxy group Good.
As such other copolymerizable monomers, for example, styrene, vinyl toluene, α-methylstyrene, α-hydroxymethylstyrene, α-hydroxyethylstyrene, acrylonitrile, methacrylonitrile, methallyl alcohol, allyl Monomer having a polymerizable double bond such as alcohol, ethylene, propylene, 4-methyl-1-pentene, vinyl acetate, 2-hydroxymethyl-1-butene, methyl vinyl ketone, N-vinyl pyrrolidone, N-vinyl carbazole, etc. Body etc. can be mentioned.
These other monomers (constituent units) may have only one type or two or more types.

The content of structural units derived from these other copolymerizable monomers is preferably 0 to 20% by mass with respect to 100% by mass of the methacrylic resin, and from the viewpoint of weatherability, 10% by mass. It is more preferable that it be less than%, and it is further preferable that it be less than 7% by mass.
The methacrylic resin in the present embodiment may have only one type of the above-mentioned copolymerizable other monomer-derived structural unit, or may have two or more types.

  As a method of producing a methacrylic resin having a lactone ring structural unit, a method of forming a lactone ring structure by a cyclization reaction after polymerization is used, but in order to accelerate the cyclization reaction, solution polymerization using a solvent is preferable .

Examples of the solvent used for the polymerization include aromatic hydrocarbons such as toluene, xylene and ethylbenzene; ketones such as methyl ethyl ketone and methyl isobutyl ketone; and the like.
These solvents may be used alone or in combination of two or more.

In the present embodiment, a method of additionally adding a polymerization solvent having different chain transfer ability during polymerization can also be preferably used for the purpose of obtaining a resin having controlled solid dynamic viscoelasticity characteristics.
Generally, in radical polymerization in solution, it is known that the degree of chain transfer reaction varies depending on the type of solvent used. (For example, Kodansha Publishing: Synthesis of Polymers (top) 1st Part: radical polymerization reference)
In practice, it differs depending on each reaction condition, so it needs to be confirmed in the system actually used, but from the study results of the present inventors, for example, the initial stage of polymerization (for example, immediately after the start of addition of the polymerization initiator) The solvent such as methyl isobutyl ketone having a relatively small chain transfer ability is used during the arbitrary time period from 1 to 2 hours, and any of the above selected during the polymerization (for example, immediately after the start of addition of the polymerization initiator to 2 hours) After time, there may be mentioned, for example, a method of additionally adding a solvent such as xylene and ethylbenzene having a relatively large chain transfer ability.

  In addition, an alcohol such as methanol, ethanol or isopropanol may be used in combination as a polymerization solvent as long as the dissolution of the polymerization product during polymerization is not inhibited.

  The amount of solvent at the time of polymerization is not particularly limited as long as polymerization proceeds and gelation can be suppressed, but when the total amount of the monomers to be blended is 100 parts by mass, 10 to 100 parts by mass It is preferable to do. The amount is more preferably 25 to 100 parts by mass, further preferably 40 to 100 parts by mass, and still more preferably 50 to 100 parts by mass.

In the present embodiment, in order to obtain a resin having a controlled solid dynamic viscoelasticity property, 100 parts by mass when the total amount of monomers to be blended is 100 parts by mass in the amount of solvent at the time of polymerization. A method in which polymerization is carried out while appropriately changing the solvent concentration during polymerization while keeping the following range can be preferably used.
More specifically, for example, the polymerization solvent to be used is 100 parts by mass, and 40 to 90 parts by mass, preferably 40 to 60 parts by mass of the polymerization solvent is blended before the start of the polymerization, Immediately after or 6 hours after the addition of the initiator, the remaining 60 to 40 parts by mass may be blended. Furthermore, finally, when the total amount of monomers to be blended in the polymerization solution is 100 parts by mass, the solvent amount of the polymerization solvent is 100 parts by mass or less, more preferably 95 parts by mass or less And the like can be exemplified.
By adopting this method, a resin and resin composition having controlled solid dynamic viscoelasticity tend to be easily prepared, and a stretched film excellent in stretchability and quality is stably produced. It is preferable because it is possible to

  The polymerization temperature is not particularly limited as long as the polymerization proceeds, but is preferably 50 to 200 ° C., more preferably 80 to 150 ° C., still more preferably 90 to 130 ° C. from the viewpoint of productivity. is there.

In the present embodiment, in order to obtain a resin having controlled solid dynamic viscoelastic properties, a method of changing the polymerization temperature at an appropriate stage during the polymerization can be preferably used.
More specifically, in the initial stage of polymerization (for example, up to 1 hour from the start of addition of the polymerization initiator), select a lower polymerization temperature within the above temperature range, and during the polymerization (for example, start of addition of the polymerization initiator) From 1 hour later), the polymerization temperature can be changed to a higher polymerization temperature within the above temperature range to continue polymerization. The difference between the higher polymerization temperature and the lower polymerization temperature is preferably 10 to 30 ° C., more preferably 10 to 20 ° C.
By adopting this method, a resin and resin composition having controlled solid dynamic viscoelasticity tend to be easily prepared, and a stretched film excellent in stretchability and quality is stably produced. It is preferable because a resin and resin composition that can be obtained can be obtained.

  The polymerization time is not particularly limited as long as the target conversion rate is satisfied, but it is preferably 0.5 to 10 hours, more preferably 1 to 8 hours from the viewpoint of productivity and the like.

  At the time of the polymerization reaction, polymerization may be carried out by adding a polymerization initiator or a chain transfer agent, if necessary.

Although it does not specifically limit as a polymerization initiator, For example, the polymerization initiator etc. which were disclosed by the preparation method of the methacrylic resin which has a structural unit derived from the said N-substituted maleimide monomer can be utilized.
These polymerization initiators may be used alone or in combination of two or more.
The amount of the polymerization initiator used may be appropriately set according to the combination of monomers, reaction conditions, etc., and is not particularly limited, but the total amount of monomers used for polymerization is 100 parts by mass. It may be 0.05 to 1 part by mass.

These polymerization initiators may be added at any stage as long as the polymerization reaction is in progress.
In the present embodiment, the type of initiator, the amount of initiator, the polymerization temperature, etc., so that the ratio of the total amount of radicals generated from the polymerization initiator to the total amount of unreacted monomers remaining in the reaction system is always below a certain value. It is preferable to select as appropriate.
In particular, in this embodiment, the addition amount per unit time of the polymerization initiator per unit time at least once in the first half of the time from the start of the addition of the polymerization initiator to the end of the addition (polymerization initiator addition time) It is preferable to make it smaller than the addition amount per time.
By employing this method, it is possible to suppress the amount of oligomers or low molecular weight products formed in the late stage of polymerization, or to suppress the overheating during polymerization to achieve the stability of polymerization.

As a chain transfer agent, a chain transfer agent used in general radical polymerization can be used. For example, the chain transfer agent disclosed in the method for preparing a methacrylic resin having a structural unit derived from the N-substituted maleimide monomer is used. it can.
These may be used alone or in combination of two or more.
These chain transfer agents may be added at any stage as long as the polymerization reaction is in progress, and is not particularly limited.
The amount of chain transfer agent used is not particularly limited as long as the desired degree of polymerization can be obtained under the polymerization conditions used, but preferably 100 parts by mass of the total amount of monomers used for polymerization When used, it may be 0.05 to 1 part by mass.

In this embodiment, a chain transfer agent is added at the initial stage of polymerization (for example, 1 to 2.5 hours after the start of addition of the polymerization initiator) in order to obtain a resin having controlled solid dynamic viscoelasticity characteristics. It is also possible to preferably use a method in which a chain transfer agent is additionally added when polymerization conversion reaches a range not exceeding 60% after polymerization initiation. In addition, as a timing of said additional addition, it is preferable to set it as the time of the range of 20-55% of a polymerization conversion ratio, More preferably, it is the time of the range of 20-50%.
The polymerization conversion rate in the present embodiment means that a part of the polymerization solution is collected, dissolved in chloroform, and the amount of monomer remaining in the polymerization solution is single monomer remaining in the sample using gas chromatography. The body concentration was measured to determine the total mass (a) of the monomers remaining in the polymerization solution. And it says the value calculated | required by calculation formula (ba) / bx100 from this gross mass (a) and the gross mass (b) of the monomer added by the time of extract | collecting a sample.
When a chain transfer agent is added with a polymerization conversion exceeding 60%, the low molecular weight component tends to increase more, and the resin and resin composition having controlled solid dynamic viscoelasticity characteristics of the present invention Is not likely to be obtained.
By adopting this method, a resin and resin composition having controlled solid dynamic viscoelasticity tend to be easily prepared, and a stretched film excellent in stretchability and quality is stably produced. It is preferable because a resin and resin composition that can be obtained can be obtained.

The methacrylic resin having a lactone ring structural unit in the present embodiment can be obtained by performing a cyclization reaction after the completion of the polymerization reaction. Therefore, it is preferable to use for a lactone cyclization reaction in the state containing a solvent, without removing a polymerization solvent from a polymerization reaction liquid.
The copolymer obtained by the polymerization undergoes a cyclocondensation reaction between a hydroxyl group (hydroxyl group) present in the molecular chain of the copolymer and an ester group by being heat-treated to give a lactone ring structure. Form

In the heat treatment for forming a lactone ring structure, a vacuum device for removing an alcohol which may be by-produced by cyclization condensation, a reaction device equipped with a degassing device, an extruder equipped with a degassing device, etc. can also be used .
When forming the lactone ring structure, if necessary, heat treatment may be performed using a cyclization condensation catalyst in order to accelerate the cyclization condensation reaction.
Specific examples of the cyclization condensation catalyst include, for example, methyl phosphite, ethyl phosphite, phenyl phosphite, dimethyl phosphite, diethyl phosphite, diphenyl phosphite, trimethyl phosphite, phosphite Phosphoric acid monoalkyl esters such as triethyl phosphate, dialkyl esters or triesters; methyl phosphate, ethyl phosphate, 2-ethylhexyl phosphate, octyl phosphate, isodecyl phosphate, lauryl phosphate, stearyl phosphate, phosphoric acid Isostearyl, dimethyl phosphate, diethyl phosphate, di-2-ethylhexyl phosphate, diisodecyl phosphate, dilauryl phosphate, distearyl phosphate, diisostearyl phosphate, trimethyl phosphate, triethyl phosphate, triisodecyl phosphate, Trilauryl phosphate, tristearyl phosphate, triisostearyl phosphate Phosphoric acid monoalkyl esters and the like, dialkyl ester or trialkyl esters; and the like are.
These may be used alone or in combination of two or more.
The use amount of the cyclization condensation catalyst is not particularly limited, but is preferably 0.01 to 3 parts by mass, and more preferably 0.05 to 3 parts by mass with respect to 100 parts by mass of the methacrylic resin, for example. It is 1 part by mass.
When the amount of the catalyst used is 0.01 parts by mass or more, it is effective for improving the reaction rate of the cyclization condensation reaction, and when the amount of the catalyst used is 3 parts by mass or less, the obtained polymer is colored In addition, it is effective to prevent the polymer from being crosslinked and difficult to melt-mold.

  The addition timing of the cyclization condensation catalyst is not particularly limited. For example, it may be added at the initial stage of the cyclization condensation reaction, may be added during the reaction, or both may be added. Good.

In carrying out the cyclization condensation reaction in the presence of a solvent, simultaneously carrying out the degassing is also preferably used.
The apparatus used when the cyclization condensation reaction and the degassing step are simultaneously carried out is not particularly limited, but a devolatilizing apparatus comprising a heat exchanger and a degassing tank, a vented extruder, and a devolatilizing apparatus. Preferably, the apparatus and the extruder are arranged in series, and more preferably a vented twin-screw extruder.

The vented twin-screw extruder to be used is preferably a vented extruder having a plurality of vent ports.
The reaction temperature in the case of using a vented extruder is preferably 150 to 350 ° C., more preferably 200 to 300 ° C. When the reaction temperature is 150 ° C. or higher, it is effective to prevent the cyclocondensation reaction from becoming insufficient and the residual volatile content increases, and when the reaction temperature is 350 ° C. or lower, it is obtained It is effective in suppressing the coloring and decomposition of the polymer.
The degree of vacuum in the case of using a vented extruder is preferably 10 to 500 Torr, more preferably 10 to 300 Torr. If the degree of vacuum is 500 Torr or less, volatile components tend not to remain. On the contrary, if the degree of vacuum is 10 Torr or more, industrial implementation is relatively easy.

When carrying out the above-mentioned cyclization condensation reaction, it is also preferable to add an alkaline earth metal and / or an amphoteric metal salt of an organic acid at the time of granulation in order to deactivate the remaining cyclization condensation catalyst.
As an alkaline earth metal and / or amphoteric metal salt of an organic acid, for example, calcium acetyl acetate, calcium stearate, zinc acetate, zinc octylate, zinc 2-ethylhexylate and the like can be used.
After undergoing the cyclocondensation reaction step, the methacrylic resin is melted and extruded in the form of a strand from an extruder having a porous die attached thereto, using a cold cut method, an airborne hot cut method, an underwater strand cut method, and an under water cut method. Process into pellets.

  The methacrylic resin in the present embodiment preferably has at least one ring structural unit selected from the group consisting of a structural unit derived from an N-substituted maleimide monomer, and a lactone ring structural unit, and among them, in particular, others It is particularly preferable to have a structural unit derived from an N-substituted maleimide monomer, from the viewpoint of easily controlling optical properties such as photoelastic coefficient without blending thermoplastic resins.

(Method for producing methacrylic resin composition)
The method for producing the methacrylic resin composition of the present embodiment is not particularly limited as long as a composition satisfying the requirements of the present invention can be obtained.
When a melt extrusion method is adopted as a method of preparing the composition, it is preferable to adopt a method of preparing the composition while removing residual volatile components as much as possible using a vented extruder.

  Moreover, when using the methacrylic resin composition of this embodiment for a film use etc., in order to reduce a foreign material, a polymerization reaction process, a liquid-liquid separation process, a liquid-solid separation process, a devolatilization process, granulation Preparation using, for example, a sintered filter with a filtration accuracy of 1.5 to 20 μm, a pleated filter, and a leaf disc type polymer filter, etc., in any one or more steps of the step and the forming step. Is also a preferred method.

Even when any method is selected, it is preferable to reduce the oxygen and moisture as much as possible when producing the methacrylic resin composition.
For example, as the dissolved oxygen concentration in the polymerization solution in solution polymerization, a concentration of less than 300 ppm in the polymerization step is less than 1% by volume as the oxygen concentration in the extruder in the preparation method using an extruder etc. It is preferable to set the ratio to less than 0.8% by volume.
The water content of the methacrylic resin is preferably adjusted to 1000 mass ppm or less, more preferably 500 mass ppm or less.
Within these ranges, it is relatively easy to prepare a composition meeting the requirements of the present invention, which is advantageous.

For example, when a production method using an extruder is adopted, the pelletized methacrylic resin as a raw material is heated under reduced pressure or dehumidified air and dried in advance to remove water as much as possible. It is preferable to use it. At that time, when various antioxidants and additives to be described later are mixed, it is preferable that these various antioxidants and additives themselves be mixed after sufficiently reducing the amount of water contained.
Furthermore, in order to minimize the mixing of oxygen in the extruder and to prevent oxidation of the composition in the molten state, an inert gas such as nitrogen gas is allowed to flow into the extruder, and a vented extruder is used. It is preferable to carry out while exhausting under reduced pressure.
As drying temperature, such as a raw material in that case, 40-120 degreeC is preferable, More preferably, it is 70-100 degreeC.
The degree of pressure reduction is not particularly limited, and the degree of pressure reduction may be appropriately selected.

The methacrylic resin composition melt-kneaded into a molten state using an extruder is melt extruded from a porous die and pelletized.
At that time, as a granulation method which can be used, for example, an airborne hot cut method, a watering hot cut method, a cold cut method, an underwater strand cut method, an under water cut method and the like can be mentioned.

As in this embodiment, in order to obtain a methacrylic resin composition in which the change in loss tangent in a high temperature range is highly controlled, the composition in the molten state under high temperature is exposed to air as much as possible. It is preferable to adopt a granulation method that can be solidified rapidly by cooling without being set.
For this purpose, for example, a watering hot cut system, a cold cut system, an underwater strand cut system, an underwater cut system, etc. are preferable, but from the viewpoint of productivity and granulator cost, generally water cooled strands The cut method is more preferable.
In such a case, the temperature of the molten resin is lowered as much as possible, and the residence time from the porous die outlet to the surface of the cooling water is minimized, and the temperature of the cooling water is as high as possible. More preferably, granulation is carried out.
For example, the temperature of the molten resin is preferably 240 to 300 ° C., more preferably 250 to 290 ° C., and the residence time from the porous die outlet to the cooling water surface is preferably 5 seconds or less, more preferably 3 seconds or less The temperature of the cooling water is preferably 30 to 80 ° C., more preferably 40 to 60 ° C.

-Other thermoplastic resins-
When preparing the methacrylic resin composition of the present embodiment, it is also possible to blend another thermoplastic resin for the purpose of adjusting the birefringence and improving the flexibility without impairing the purpose of the present embodiment. it can.
As other thermoplastic resins, for example, polyacrylates such as polybutyl acrylate; polystyrene, styrene-methyl methacrylate copolymer, styrene-butyl acrylate copolymer, styrene-acrylonitrile copolymer, acrylonitrile-butadiene-styrene Styrene-based polymers such as block copolymers; and further, for example, JP-A-59-202213, JP-A-63-27516, JP-A-51-129449, JP-A-52-56150. Acrylic rubber particles having a three- to four-layer structure described in JP-A No. 60-17406 and JP-A-8-245854; and those described in WO 2014-002491. And methacrylic rubber-containing graph / copolymer particles obtained by multi-stage polymerization; It is.
Among these, from the viewpoint of obtaining good optical properties and mechanical properties, a composition compatible with a styrene-acrylonitrile copolymer or a methacrylic resin containing a structural unit (X) having a ring structure in its main chain The rubber-containing graft copolymer particle which has the graft part which becomes in the surface layer is preferable.
The average particle diameter of the aforementioned acrylic rubber particles, methacrylic rubber-containing graph / copolymer particles, and rubber polymer is the impact strength, optical characteristics, etc. of the film obtained from the methacrylic resin composition of this embodiment. It is preferable that it is 0.03-1 micrometer from a viewpoint of heightening, More preferably, it is 0.05-0.5 micrometer.

  The content of the other thermoplastic resin is preferably in the range of 0 to 50 parts by mass, more preferably 0 to 25 parts by mass, based on 100 parts by mass of the methacrylic resin.

-Antioxidant-
In the methacrylic resin composition according to the present embodiment, a hindered phenol type antioxidant, a phosphorus type antioxidant, and a sulfur type antioxidant can be used to exhibit the original polymer characteristics of the methacrylic resin of the present embodiment. It is preferable to add an antioxidant such as an agent.
These may be used alone or in combination of two.

Specific examples of hindered phenolic antioxidants include, but are not limited to, for example, pentaerythritol tetrakis [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate], Thiodiethylene bis [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate], octadecyl-3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate, 3,3 ', 3'', 5, 5', 5 ''-hexa-tert-butyl-a, a ', a "-(mesitylene-2,4,6-triyl) tri-p-cresol, 4,6 -Bis (octylthiomethyl) -o-cresol, 4,6-bis (dodecylthiomethyl) -o-cresol, ethylenebis (oxyethylene) bis [3- (5-t) rt-Butyl-4-hydroxy-m-tolyl) propionate], hexamethylene bis [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate], 1,3,5-tris (3,3, 5-di-tert-butyl-4-hydroxybenzyl) -1,3,5-triazine-2,4,6 (1H, 3H, 5H) -trione, 1,3,5-tris [(4-tert-) Butyl-3-hydroxy-2,6-xillin) methyl] -1,3,5-triazine-2,4,6 (1H, 3H, 5H) -trione, 2,6-di-tert-butyl-4- (4,6-bis (octylthio) -1,3,5-triazin-2-ylamine) phenol, acrylic acid 2- [1- (2-hydroxy-3,5-di-tert-pentylphenyl) ethyl]- 4, - di -tert- pentylphenyl, acrylic acid 2-tert-butyl-4-methyl-6- (2-hydroxy -3-tert-butyl-5-methylbenzyl) phenyl and the like.
In particular, pentaerythritol terakis [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate], octadecyl-3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate, Acrylic acid 2- [1- (2-hydroxy-3,5-di-tert-pentylphenyl) ethyl] -4,6-di-tert-pentylphenyl is preferred.

Moreover, the said hindered phenol type antioxidant may use a commercially available phenol type antioxidant, As such commercially available phenol type antioxidant, although it is not limited to the following, For example, Irganox 1010 (Irganox 1010: pentaerythritol tetrakis [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate], manufactured by BASF, Inc.), Irganox 1076 (Irganox 1076: octadecyl-3- ( 3,5-di-t-butyl-4-hydroxyphenyl) propionate, manufactured by BASF AG, Irganox 1330 (Irganox 1330: 3, 3 ', 3'', 5, 5', 5 ''-hexa-t -Butyl-a, a ', a''-(mesitylene-2,4,6-triyl)tri-p-cresol; Manufactured by ASF, Irganox 3114: 1,3,5-tris (3,5-di-t-butyl-4-hydroxybenzyl) -1,3,5-triazine-2,4,6 (1H) , 3H, 5H) -trione, manufactured by BASF, Irganox 3125 (Irganox 3125, manufactured by BASF), Adekastab AO-60 (pentaerythritol tetrakis [3- (3,5-di-t-butyl-4-hydroxyl) Phenyl) propionate], ADEKA company), Adekastab AO-80 (3, 9-bis {2- [3- (3-t-butyl-4-hydroxy-5-methylphenyl) propionyloxyoxy] -1, 1 -Dimethylethyl} -2,4,8,10-tetraoxaspiro [5.5] undecane (manufactured by ADEKA Corporation), Sumilizer BHT (Sumilizer BHT, manufactured by Sumitomo Chemical Co., Ltd.), cyanox 1790 (Cyanox 1790, manufactured by Cytech), Sumilizer GA-80 (Sumilizer GA-80, manufactured by Sumitomo Chemical), Sumilizer GS (Sumilizer GS: acrylic acid 2- [1- (2) -Hydroxy-3,5-di-tert-pentylphenyl) ethyl] -4,6-di-tert-pentylphenyl, manufactured by Sumitomo Chemical Co., Ltd., Sumilizer GM (Sumilizer GM: 2-tert-butyl-4-methyl acrylate) -6- (2-hydroxy-3-tert-butyl-5-methylbenzyl) phenyl, manufactured by Sumitomo Chemical Co., Ltd., vitamin E (manufactured by Eisai Co., Ltd.), and the like.
Among these commercially available phenolic antioxidants, Irganox 1010, Adekastab AO-60, Adekastab AO-80, Irganox 1076, and Sumilyzer GS are preferable from the viewpoint of the heat stability imparting effect of the resin.
These may be used alone or in combination of two or more.

  Examples of phosphorus-based antioxidants include those classified into phosphites and phosphonites.

  Specific examples of phosphorus-based antioxidants for phosphites include, but are not limited to, for example, tris (2,4-di-t-butylphenyl) phosphite, tris (2,6-di) -Tert-Butylphenyl) phosphite, tris (2,4-di-tert-butyl-5-methylphenyl) phosphite, bis (2,4-di-tert-butyl-6-methylphenyl) ethyl phosphite, 2,2'-Methylenebis (4,6-di-t-butylphenyl) octyl phosphite, bis (2,6-di-t-butyl-4-methylphenyl) pentaerythritol diphosphite, cyclic neopentane Tetrayl bis (2,6-di-t-butyl-4-methylphenyl) phosphite and the like can be mentioned.

  For example, Irgafos 168 (Irgafos 168: tris (2,4-di-t-butylphenyl) phosphite, manufactured by BASF), Irgafos 12 (Irgafos 12: tris [2- [2 [2,4,8,10-Tetra-t-butyldibenzo [d, f] [1,3,2] dioxaphosphepin-6-yl] oxy] ethyl] amine, manufactured by BASF, Irgafos 38 ( Irgafos 38: bis (2,4-di-tert-butyl-6-methylphenyl) ethyl phosphite, manufactured by BASF, Adekastab HP-10 (ADKSTAB HP-10: 2,2'-methylenebis (4,6-di-) tert-Butylphenyl) octyl phosphite: manufactured by ADEKA Co., Ltd., Adekastab PEP24G (A EKASTAB PEP 24 G: cyclic neopentanetetrayl bis (2,4-di-tert-butylphenyl) phosphite: manufactured by ADEKA Corporation, adecastab PEP 36 (ADKSTAB PEP 36: bis (2, 6-di-t-butyl-4) -Methylphenyl) pentaerythritol diphosphite: manufactured by ADEKA Corporation, Adekastab PEP 36A (ADKSTAB PEP 36A: bis (2,6-di-t-butyl-4-methylphenyl) pentaerythritol diphosphite: manufactured by ADEKA Corporation) Adekastab PEP-8 (ADKSTAB PEP-8: cyclic neopentanetetrayl bis (2,4-di-tert-butylphenyl phosphite: manufactured by ADEKA Co., Ltd.), Sumilizer GP (Sumil) zerGP: (6- [3- (3-t-butyl-4-hydroxy-5-methylphenyl) propoxy] -2,4,8,10-tetra-t-butyldibenz [d, f] [1,3,3, 2) Dioxaphosphepin, manufactured by Sumitomo Chemical Co., Ltd., and the like.

Specific examples of phosphorus-based antioxidants for phosphonites include, for example, tetrakis (2,4-di-tert-butylphenyl) 4,4′-biphenylenediphosphonite, tetrakis (2,4-di-tert-butyl) -5- methylphenyl) 4, 4'- biphenylene diphosphonite etc. can be illustrated.
It may be a commercially available phosphorus antioxidant, Hostanox P-EPQ (P-EPQ: tetrakis (2,4-di-tert-butylphenyl) 4,4′-biphenylene diphosphonite: manufactured by Clariant Co. Ltd.) And GSY P101 (tetrakis (2,4-di-t-butyl-5 methylphenyl) 4,4′-biphenylene diphosphonite: manufactured by Sakai Chemical Co., Ltd.).

Further, specific examples of the sulfur-based antioxidant are not limited to the following, and examples thereof include 2,4-bis (dodecylthiomethyl) -6-methylphenol (Irganox 1726, manufactured by BASF), Irganox 1520 L (manufactured by BASF), 2,2-bis {[3- (dodecylthio) -1-oxopropoxy] methyl} propane-1,3-diylbis [3-dodecylthio] propionate] (ADEKA STAB AO-412S, Adeka company) Product), 2,2-bis {[3- (dodecylthio) -1-oxopropoxy] methyl} propane-1,3-diylbis [3-dodecylthio] propionate] (cheminox PLS, manufactured by Chemipro Chemical Industries, Ltd.), di (tridecyl) And 3,3'-thiodipropionate (AO-503, manufactured by ADEKA Corporation). Be
Among these commercially available sulfur antioxidants, Adekastab AO-412S and Cheminox PLS are preferable from the viewpoint of the heat stability imparting effect of the resin, the combined effect with various antioxidants, and the handleability.
These sulfur-based antioxidants may be used alone or in combination of two or more.

  The content of the antioxidant may be any amount as long as the effect of improving the thermal stability can be obtained, and if the content is excessive, problems such as bleeding out during processing may occur. The content is preferably 5 parts by mass or less, more preferably 3 parts by mass or less, still more preferably 1 part by mass or less, still more preferably 0.8 parts by mass or less, based on 100 parts by mass of the methacrylic resin The amount is more preferably 0.01 to 0.8 parts by mass, particularly preferably 0.01 to 0.5 parts by mass.

-Other additives-
Other additives may be contained in the methacrylic resin composition according to the present embodiment as long as the effects of the present embodiment are not significantly impaired.
The other additives are not particularly limited, but, for example, inorganic fillers; pigments such as iron oxide; stearic acid, behenic acid, zinc stearate, calcium stearate, magnesium stearate, lubricants such as ethylene bis stearoamide -Releasing agents: Softeners such as paraffinic process oils, naphthenic process oils, aromatic process oils, paraffins, organic polysiloxanes, mineral oils, etc.-Plasticizers with hindered amine light stabilizers; Benzotriazole ultraviolet light absorbers; Higher alcohols such as cetyl alcohol and stearyl alcohol; Release agents such as glycerin higher fatty acid esters such as stearic acid monoglyceride and diglyceride stearate; flame retardants; antistatic agents; reinforcement of organic fibers, glass fibers, carbon fibers, metal whiskers, etc. Agents; coloring agents; Other additives; or mixtures thereof.

  Hereinafter, the characteristics of the methacrylic resin composition of the present embodiment will be described in detail.

The methacrylic resin composition of the present embodiment preferably has a weight-average molecular weight (Mw) in terms of polymethyl methacrylate as measured by a GPC measurement method of 120,000 to 260,000, more preferably 120,000 to 240,000, more preferably 120,000 to 230,000.
When the weight average molecular weight (Mw) is in this range, the balance between mechanical strength and moldability is excellent, which is preferable.
Specifically, the weight average molecular weight (Mw) of the methacrylic resin composition can be measured by the method described in the examples below.

-Dynamic viscoelastic property-
The methacrylic resin composition containing the structural unit (X) having a ring structure in the main chain of the present embodiment exhibits a maximum value in the temperature dispersion spectrum of loss elastic modulus when subjected to dynamic viscoelasticity measurement (T _{G "max),} the temperature showing the maximum value at a temperature variance spectrum of the loss tangent _{(T tanδmax),} in the range from a temperature _{(T tanδmax)} showing a maximum in the temperature variance spectrum of the loss tangent to 50 ° C. higher temperature than the said temperature The temperature (T _{tan δ min} ) showing the minimum value of the loss tangent is shown.
FIG. 1 shows a temperature dispersion spectrum of a typical loss elastic modulus and a temperature dispersion spectrum of a loss tangent obtained when the methacrylic resin composition of the present embodiment is subjected to dynamic viscoelasticity measurement. In FIG. 1, in particular, with respect to the vertical axis, the vertical axis on the right side represents loss tangent (−), and the vertical axis on the left side represents loss elastic modulus (Pa).
In this embodiment, the loss tangent is in the range from the above-mentioned temperature (T _{tan δ max} ), the temperature (T _{tan δ max} ), the temperature (T _{tan δ min} ), and further, the above temperature (T _{tan δ max} ) It is preferable that a temperature difference (ΔT) indicating a minimum value of to a value of a loss tangent 10% higher than the minimum value satisfies and satisfies the conditions shown below.

First, in the present embodiment, the temperature (T _{G ′ ′ max} ) at which the maximum value is exhibited in the temperature dispersion spectrum of the loss elastic modulus is in the range of 120 to 160 ° C., preferably in the range of 120 to 155 ° C. More preferably, it is in the range of 120 to 150 ° C.
When the temperature at which the maximum value of the loss elastic modulus is shown is in this range, sufficient heat resistance as a film can be exhibited, which is preferable.

Second, the minimum value (tan δ min) of the loss tangent in the range from the temperature (T _{tan δ max} ) at which the temperature is maximum to the temperature dispersion spectrum of the loss tangent to the temperature 50 ° C. higher than the temperature is 0.70 to 1.20. It is preferably in the range of 0.70 to 1.16, more preferably in the range of 0.70 to 1.14, and particularly preferably in the range of 0.80 to 1.12.
It is preferable that the minimum value (tan δ min) in the range from the temperature (T _{tan δ max} ) showing the maximum value of the loss tangent to the temperature further _{raised by} 50 ° C. is in this range, since a high quality stretched film can be stably produced.

Third, in the range from the temperature (T _{tan δ max} ) at which the maximum value is shown in the temperature dispersion spectrum of loss tangent to the temperature 50 ° C. higher than the temperature, the value of the loss tangent is 10% higher than the minimum value of the loss tangent It is preferable that the difference ((DELTA) T) of the temperature which shows to is the range of 12-24 degreeC, More preferably, it is the range of 13-23 degreeC, More preferably, it is 14-22 degreeC.
When the temperature difference (ΔT) showing a loss tangent value 10% higher than the minimum value in the range from the temperature (T _{tan δmax} ) showing the maximum value of the loss tangent to the temperature 50 ° C. higher is in this range, high grade It is preferable because the selection range of the stretching temperature at which a stretched film can be obtained can be expanded, and further, a high quality stretched film can be stably produced without being influenced by a slight temperature environment fluctuation at the time of stretching.

By the way, when preparing a stretched film using a resin composition containing a methacrylic resin having a ring structure in the main chain, two maximum values appearing in the temperature dispersion spectrum obtained by the above-described dynamic viscoelasticity measurement are _{Where the} stretching operation is generally performed in the high temperature range including the indicated temperatures (T _{G ′ ′ max} and T _{tan δ max} ), the inventors have found that the temperature dispersion spectrum of the loss tangent is the viscous nature of the resin and It has been found that the above-mentioned various problems can be solved by providing a material in which the change of the loss tangent in the above-mentioned temperature range is highly controlled because it represents the ratio to the elastic property.
The method of controlling the behavior of loss tangent in the above-mentioned temperature range of the methacrylic resin composition having a ring structure in the main chain is not particularly limited as long as a composition satisfying the above-mentioned characteristics can be prepared. In radical polymerization in solution polymerization by solution or semi-batch method, polymerization temperature, monomer concentration, addition amount and addition rate of polymerization initiator, addition time, addition amount of chain transfer agent, addition rate, addition time, and solvent used The method which superposes | polymerizes, changing suitably polymerization conditions, such as a kind and density | concentration, in the middle of superposition | polymerization, is mentioned.

The reason why the higher order structure of the solid in the above-mentioned temperature range can be controlled by this method is not clear, but the molecular weight and molecular weight distribution of the resulting resin composition, the amount of components having a weight average molecular weight of less than 10000, composition distribution, It is presumed that the regular distribution etc. acted in combination.
When a stretched film is produced using a methacrylic resin composition in which the high temperature range in the temperature dispersion spectrum is highly controlled, the various problems described above at the time of stretching can be solved, and various temperature fluctuations at the time of stretching It turned out that it could correspond, too.

Here, in the dynamic viscoelasticity measurement, a storage elastic modulus (sometimes referred to as “E ′” or “G ′”) may be obtained by applying a periodic micro strain to the sample and measuring a response thereto. Loss modulus (sometimes referred to as "E" or "G"), and loss tangent (sometimes referred to as "E" / E '"," G "/ G'", or "tan δ" ) Is to be measured.
The storage elastic modulus represents the degree to which the energy generated by the external force and strain is stored therein as an elastic index, and the loss elastic modulus dissipates the heat generated by the external force and strain as heat as a viscous index The loss tangent (tan δ), which represents the degree and is a ratio of loss elastic modulus to storage elastic modulus, is used as an indicator showing whether the state of the sample is viscous or elastic.

And in dynamic viscoelasticity measurement, the temperature dispersion spectrum of each index can be obtained by using a method of changing the measurement temperature at a constant velocity.
For example, in the case where the sample to be measured is an amorphous polymer such as acrylic resin, generally, from the low temperature side, it is derived from the γ-dispersion derived from the motion of the polymer side chain and the local motion of the main chain A relaxation mechanism called α dispersion (also referred to as main dispersion) derived from β dispersion, micro brown motion of the main chain is observed.

Hereinafter, the temperature dispersion spectrum of the resin composition will be described with reference to FIG.
At low temperatures, the energy given to the sample in the glassy state is only partially dissipated as energy associated with the local motion of the molecular chains, but most of it is stored internally.
When the temperature gradually rises from this point to near the glass transition temperature, the whole molecular chains in the sample suddenly begin to actively move, and the energy dissipated also increases with the temperature rise.
Then, gradually, entanglement of molecular chains in the solid begins to be released, and when the unit of motion spreads over the entire sample, a maximum value appears in the temperature dispersion spectrum of loss modulus. It is known that the temperature (T _{G ′ ′ max} ) indicating the maximum value of the loss elastic modulus usually appears in a temperature range lower than the temperature (T _{tan δmax} ) indicating the maximum value of the loss tangent (tan δ) described above .
When the temperature further rises, the entanglement of molecular chains is further dissolved, and both the storage elastic modulus and the loss elastic modulus decrease, but a maximum value appears in the temperature dispersion spectrum of the loss tangent at a temperature at which the magnitude of the inclination is exchanged. The temperature (T _{tan δmax} ) showing the maximum value of the loss tangent may be used as a dynamic glass transition temperature (in the present embodiment, this mark is used to distinguish it from the generally used glass transition temperature). In general, the larger the tan δ value at this dynamic glass transition temperature, the more easily the resin composition is plastically deformed, and the smaller it is, the larger the repulsive force is. Therefore, the magnitude of this value may be used to evaluate the shock absorption of rubber or elastomer products.
Then, with the further rise in temperature, the entanglement between molecular chains is further released, the resin starts to flow, and the storage elastic modulus is significantly reduced. Therefore, in both temperature dispersion profiles of the storage elastic modulus and the loss elastic modulus, the magnitude of the inclination is replaced again, and as a result, the loss tangent represented by the ratio of the loss elastic modulus and the storage elastic modulus starts to increase Thus, the minimum value (tan δ min) of the loss tangent appears in a temperature range higher than the temperature (T _{tan δ max} ) indicating the maximum value of the loss tangent. It is suggested that in the temperature range higher than the temperature (T _{tan δ min} ) exhibiting this local minimum, the resin composition is no longer in the solid state but has changed to the molten state with fluidity.
In this embodiment, in view of the above-mentioned circumstances, stretching is performed by precisely controlling the value of the loss tangent at the temperature (T _{tan δ min} ) indicating the minimum value of the loss tangent and the change of the loss tangent in the temperature range before and after it. The state of entanglement of molecular chains at the time can be optimized, and as a result, a stretched film excellent in quality can be stably produced.

Conventionally, a glass transition temperature based on specific heat change using DSC, which is widely used as a measurement method of glass transition temperature, and a temperature (T _{G ′ ′ max} ) indicating a maximum value of loss elastic modulus determined by this dynamic viscoelasticity Although many studies have been conducted on the relationship with the dynamic glass transition temperature based on the temperature (T _{tan δmax} ) at which the maximum value of the loss tangent and the maximum value of the loss tangent are shown, no clear conclusion has been reached at this time.
Generally, the information obtained by DSC measurement used as a measurement means of glass transition temperature includes only the temperature of the change point of specific heat, whereas the information obtained by dynamic viscoelasticity measurement is a change of viscoelasticity Since it includes changes in polymer properties such as elastic modulus near the temperature of the change point as well as the temperature of the point, it can be effectively used for optimization of the resin used in film stretching processing etc. that performs thermal processing in the solid state. It is considered to be a thing.

As a method of measuring the temperature dispersion spectrum of dynamic viscoelasticity, the following method can be used.
Preparation of samples: Test pieces of 50 mm in length, 10 mm in width and 1 mm in thickness are subjected to desired treatment and placed in a predetermined environment. Measuring device: PHYSICA MCR 301: manufactured by Anton Paar Temperature control system: CTD 450: Anton Paar · Analysis software: RheoPlus Anton Paar · Measurement mode: Torsion measurement system (SRF)
・ Measurement frequency: 1 Hz
Strain amount: 0.2%
Normal force: -0.3 N
-Distance between clamps: 38 mm
・ Measurement temperature range: 30 to 190 ° C
Temperature rising rate: 2 ° C./min More specific measurement method of temperature dispersion spectrum of dynamic viscoelasticity is as described in Examples.

-Photoelastic coefficient-
The absolute value of the photoelastic coefficient C _R of the methacrylic resin composition containing a structural unit (X) in the main chain of the present embodiment having a ring structure is preferably at 3.0 × 10 ^-12 Pa ^-1 or less, more preferably 2.0 × at ¹⁰ -12 ^{Pa -1} or less, further preferably 1.0 × ¹⁰ -12 ^{Pa -1} or less.
The photoelastic coefficient is described in various documents (see, for example, Chemical Review, No. 39, 1998 (published by Society Publishing Center)), and is defined by the following formulas (i-a) and (i-b) It is. As the value of photoelastic coefficient C _R is close to zero, it can be seen that change in birefringence due to an external force is small.
C _R = | Δn | / σ _R (i-a)
| Δn | = nx−ny (i−b)
( _Wherein , C _R is a photoelastic coefficient, σ _R is a tensile stress, | Δn | is an absolute value of birefringence, nx is a refractive index in the tensile direction, and ny is a direction perpendicular to the tensile direction in the plane Indicate the refractive index of
If the absolute value of the photoelastic coefficient C _R of the methacrylic resin composition of the present embodiment is 3.0 × 10 ⁻¹² Pa ⁻¹ or less, retardation unevenness occurs even if it is formed into a film and used in a liquid crystal display device In addition, it is possible to suppress or prevent the occurrence of light leakage and the decrease in contrast at the periphery of the display screen.
Photoelastic coefficient C _R, specifically, can be determined by the method described in Examples described later.

-Method of producing molded body-
The methacrylic resin composition of this embodiment is a known method such as injection molding, sheet molding, blow molding, injection blow molding, inflation film molding, T-die film molding, press molding, extrusion molding, foam molding, cast molding, etc. Furthermore, a shaped body can be obtained by applying a secondary processing and forming method such as pressure forming and vacuum forming.

A well-known method can be used as a method of manufacturing the film before extending | stretching (unstretched film) and a stretched film using the methacrylic resin composition of this embodiment.
As such a method, for example, a raw material resin is supplied to a single-screw or twin-screw extruder, melt-kneaded, and then a sheet extruded from a T-die is guided onto a cast roll and solidified. Subsequently, longitudinal uniaxial stretching in the mechanical flow direction is performed using a pair of rolls having different peripheral speeds, or uniaxial uniaxial stretching in the direction perpendicular to the mechanical flow (TD direction) is performed. Stretching: Sequential biaxial stretching using roll stretching and tenter stretching, simultaneous biaxial stretching by tenter stretching, biaxial stretching by tubular stretching, inflation stretching, biaxial stretching such as tenter sequential biaxial stretching; . Among them, sequential biaxial stretching comprising roll stretching and tenter stretching is preferable because the features of the methacrylic resin composition of the present embodiment can be most developed.
With regard to tenter stretching, the tenter is a film which may extend in the width direction (also referred to as a lateral direction) by extending the distance between the clips while traveling in the transport direction the clips that grip both ends in the width direction of the film. It is an apparatus for stretching.
Inside the tenter, a preheating part, a transversely extending part, a heat setting part, and a heat relaxation part as needed are provided.
Tenter clips are often combined with the drive chain and installed on an endless track. As this drive chain, there is known a type that travels in the tenter device in both directions, and a type that travels outside the tenter device on the return path. In general, since the entire apparatus can be made compact, there is a current state where the type of traveling in the tenter apparatus is also widely used.
After holding the film at the inlet of the tenter, the clip in the tenter receives a thermal history of the preheating temperature, the stretching temperature, and the heat treatment temperature, and then turns while being cooled by the cooling mechanism and returns to the inlet of the tenter again. , Again grip the film.

Here, the inside of the tenter is composed of a plurality of compartments controlled to different temperatures, and a temperature difference occurs between the clip temperature and each compartmented environmental temperature, or the stretching operation by the tenter is continued for a long time As a result, the cooling may be insufficient, or the cooling may become insufficient as the clip travels through the tenter when it returns to the inlet of the tenter. The clip temperature may not be stable when returning to the entrance of the. Therefore, the film may be broken in the vicinity of the clip, or the uniformity of the gripping force of the clip may decrease, and the film thickness distribution may increase. Therefore, the control of the clip temperature as well as the change of the clip temperature Proposals for resins that can respond flexibly are expected.
The methacrylic resin composition of the present embodiment is also useful in the sense of solving problems such as film breakage at the time of stretching caused by fluctuation of the clip temperature in the stretching step, and according to the present embodiment, mechanical It is possible to obtain a stretched film having an excellent balance of optical properties, mechanical properties and the like in the flow direction (MD direction) and the direction (TD direction) perpendicular to the mechanical flow direction.

  The final draw ratio can be judged from the heat shrinkage of the obtained molded and drawn body. The stretching ratio is preferably 0.1 to 400%, more preferably 10 to 400%, and still more preferably 50 to 350% in at least one direction. If it is less than the lower limit, the bending resistance tends to be insufficient, and if it is more than the upper limit, breakage and breakage frequently occur in the film preparation process, and the film tends not to be continuously and stably produced. By designing in this range, it is possible to obtain a preferable stretched molded product from the viewpoint of birefringence, heat resistance and strength.

The stretching temperature is preferably _{(T G''max) ℃ ~ (T} G "max +50) ℃.
Here, _{TG ′ ′ max} refers to a temperature showing a maximum value in the temperature dispersion spectrum of loss elastic modulus determined by dynamic viscoelasticity measurement of the methacrylic resin composition used to prepare a film.
By setting the stretching temperature in the above-mentioned range, a stretched film excellent in balance of optical characteristics and mechanical characteristics in the mechanical flow direction (MD direction) and the direction (TD direction) orthogonal to the mechanical flow direction can be obtained.
The lower limit of the stretching temperature is more preferably (T _{G ′ ′ max} + 5 ° C.) or more, still more preferably T _{G ′ ′ max} + 10 ° C.) or more, in order to obtain good film thickness uniformity in the obtained film. Still more preferably (T _{G ′ ′ max} + 15 ° C.) or more, particularly preferably (T _{G ′ ′ max} + 20 ° C.) or more, and the upper limit of the stretching temperature is more preferably (T _{G ′ ′ max} + 45 ° C.) The temperature is more preferably (T _{G ′ ′ max} + 40 ° C.) or less.

  In addition, when using the film of this embodiment as an optical film, in order to stabilize the optical isotropy and mechanical characteristics, it is preferable to perform heat processing (annealing) etc. after an extending | stretching process. The conditions of the heat treatment may be appropriately selected similarly to the conditions of the heat treatment performed on a conventionally known stretched film, and are not particularly limited.

  As applications of molded articles, for example, household goods, OA equipment, AV equipment, for battery electrical equipment, lighting equipment, tail lamps, meter covers, headlamps, light guide bars, automobile parts applications such as light guide rods, lenses, housing applications, sanitary ware substitutes Light guide plate, diffuser plate, polarizing plate protective film, quarter wave plate, half wave, used for sanitary applications such as liquid crystal display, plasma display, organic EL display, field emission display, rear projection television etc. A plate, a viewing angle control film, a retardation film such as a liquid crystal optical compensation film, a display front plate, a display substrate, a lens, a touch panel, etc. may be mentioned, and it can be suitably used as a transparent substrate etc. used for solar cells. In addition, in the fields of optical communication systems, optical switching systems, and optical measurement systems, it can also be used as waveguides, lenses, optical fibers, optical fiber coating materials, LED lenses, lens covers, and the like. Moreover, it can also be used as a modifier of other resin.

  Hereinafter, the contents of the present invention will be specifically described with reference to examples and comparative examples. The present invention is not limited to the following examples.

<1. Structural Unit Analysis>
Unless otherwise noted in each production example described later, structural units of the methacrylic resin produced in the production example described below were identified by ¹ H-NMR measurement and ¹³ C-NMR measurement, and the amount thereof was calculated. The measurement conditions of ¹ H-NMR measurement and ¹³ C-NMR measurement are as follows.
・ Measurement equipment: Blue Car Co., Ltd. DPX-400
Measurement solvent: CDCl3 or d6-DMSO
・ Measurement temperature: 40 ° C
When the ring structure of the methacrylic resin is a lactone ring structure, it is confirmed by the method described in JP-A-2001-151814, and when the ring structure of the methacrylic resin is a glutarimide ring structure, It confirmed by the method as described in re-publication patent WO2012 / 114718 gazette.

<2. Weight average molecular weight (Mw), molecular weight distribution (Mw / Mn)>
The weight average molecular weight (Mw) of the methacrylic resin manufactured by the below-mentioned manufacture example, and the methacrylic resin composition manufactured by the below-mentioned example and comparative example was measured on the following apparatus and conditions.
-Measuring device: gel permeation chromatography (HLC-8320 GPC) manufactured by Tosoh Corporation
·Measurement condition:
Column: One TSKguard column SuperH-H, two TSKgel SuperHM-M, and one TSKgel SuperH2500 were used in series connection in order. Column temperature: 40 ° C
Developing solvent: tetrahydrofuran, flow rate: 0.6 mL / min, 0.1 g / L of 2,6-di-t-butyl-4-methylphenol (BHT) was added as an internal standard.
Detector: RI (differential refraction) detector Detection sensitivity: 3.0 mV / min Sample: 20 mL solution of 0.02 g of methacrylic resin or methacrylic resin composition in tetrahydrofuran. Injection volume: 10 μL
Standard samples for calibration curve: The following 10 polymethyl methacrylates (manufactured by Polymer Laboratories; PMMA Calibration Kit M-M-10) having known monodispersed weight peak molecular weights and different molecular weights were used.
Weight peak molecular weight (Mp)
Standard sample 1 1,916,000
Standard sample 2 625, 500
Standard sample 3 298, 900
Standard sample 4 138, 600
Standard sample 5 60, 150
Standard sample 6 27,600
Standard sample 7 10, 290
Standard sample 8 5,000
Standard sample 9 2,810
Standard sample 10 850
Under the above conditions, the RI detection intensity was measured relative to the elution time of the methacrylic resin or methacrylic resin composition.
The weight average molecular weight (Mw) and molecular weight distribution (Mw / Mn) of the methacrylic resin, and the weight average molecular weight (Mw) of the methacrylic resin composition based on the calibration curve obtained by the measurement of the standard sample for calibration curve described above Asked for).

<3. Dynamic Viscoelastic Properties>
The method shown below was used as a measurement method of the temperature dispersion spectrum of dynamic viscoelasticity.
Preparation of Test Pieces Used for Measurement Test pieces having a length of 50 mm, a width of 10 mm, and a thickness of 1 mm were prepared by press molding using the methacrylic resin compositions obtained in Examples and Comparative Examples. And the same thermal history was given to the test piece by heat-processing the obtained test piece at the temperature of 100 degreeC for 20 hours. Then, after standing for 48 hours under the atmosphere of temperature 23 ° C. and humidity 50 RH%, the dimensions of width and thickness were measured, and subjected to measurement of temperature dispersion spectrum of dynamic viscoelasticity.
Measurement device: PHYSICA MCR 301: manufactured by Anton Paar Temperature control system: CTD450: manufactured by Anton Paar Analysis software: manufactured by RheoPlus Anton Paar Measurement mode: torsion measurement system (SRF)
・ Measurement frequency: 1 Hz
Strain amount: 0.2%
Normal force: -0.3 N
-Distance between clamps: 38 mm
・ Measurement temperature range: 30 to 190 ° C
Temperature rising rate: 2 ° C./min From the obtained temperature dispersion spectrum, T _{G ′ ′ max} , T _{tan δ max} , T _{tan δ min} , T _{tan δ min} −T _{tan δ max} , _{tan δ} min, ΔT were obtained.

<4. Photoelastic coefficient C _R >
The methacrylic resin compositions obtained in Examples and Comparative Examples were used as a press film by using a vacuum compression molding machine, to obtain a measurement sample.
As a specific sample preparation condition, after preheating for 10 minutes under a reduced pressure (about 10 kPa) at 260 ° C. using a vacuum compression molding machine (SFV-30 type, manufactured by Shinto Metal Industry Co., Ltd.), the resin composition is subjected to 260 ° C. After being compressed at about 10 MPa for 5 minutes, and after reducing the pressure and releasing the pressure, it was transferred to a cooling compression molding machine and solidified by cooling. After curing the obtained press film in a constant temperature and humidity chamber adjusted to 23 ° C. and a humidity of 60% for 24 hours or more, a test piece for measurement (thickness: about 150 μm, width: 6 mm) was cut out.
The photoelastic coefficient C _R (Pa ⁻¹ ) was measured using a birefringence measurement device described in detail in Polymer Engineering and Science 1999, 39, 2349-2357.
Similarly, a film-like test piece was placed in a film tensioner (made by Imoto Machinery Co., Ltd.) installed in a constant temperature and humidity chamber so as to be 50 mm between the chucks. Next, the device is placed so that the laser beam path of the birefringence measuring device (Retsu-100, manufactured by Otsuka Electronics Co., Ltd.) is located at the center of the film, and the strain rate is 50% / min (chuck: 50 mm, chuck moving speed: The birefringence of the test piece was measured under tensile stress at 5 mm / min.
From the relationship between the absolute value (| Δn |) of birefringence and the tensile stress (σ _R ) obtained from the measurement, the slope of the straight line is obtained by the least squares approximation, and the photoelastic coefficient (C _R ) (Pa ⁻¹ ) Calculated. For the calculation, data with an extension stress of 2.5 MPa ≦ σ _R ≦ 10 MPa was used.
C _R = | Δn | / σ _R
Here, the absolute value (| Δn |) of birefringence is a value shown below.
| Δn | = | nx-ny |
(Nx: refractive index in the stretching direction, ny: refractive index in the plane perpendicular to the stretching direction)

<5. Evaluation of stretchability of methacrylic resin composition>
From the methacrylic resin compositions obtained in the following Examples and Comparative Examples, a 50 mmφ single-piece was provided with a filter for resin filtration (leaf filter, manufactured by Nagase Sangyo Co., Ltd.) and a 480 mm wide T-die at the extruder tip. The film was prepared using a screw extruder.
As film forming conditions at that time, extruder set temperature: (T _{G ′ ′ max} +130) ° C., T die set temperature: (T _{G ′ ′ max} +125) ° C., discharge amount: 8 kg / hour, draw down ratio: 2.7 A cast roll set temperature: (T _{G ′ ′ max} ) ° C. was employed to obtain an unstretched film with a film thickness of 210 μm. In addition, as the cast roll, a ceramic surface-coated product having excellent releasability was used.

In succession to the preparation of the unstretched film, a preheating roll, a pair of stretching rolls, an infrared heater (4.2 KW, 230 V) installed between the stretching rolls (a distance of 20 mm to the film), and a transport roll Longitudinal stretching was performed on the unstretched film using a roll stretching device provided in this order.
At that time, the temperature of each roll is based on T _{G ′ ′ max} (° C.) of the resin composition used for evaluation, preheat roll temperature: (T _{G ′ ′ max} + 20) ° C., low speed side draw roll temperature: (T _{G ”max} +40) ° C., output of infrared heater: 60 to 80%, high-speed side drawing roll temperature: (T _{G ′ ′ max} + 20) ° C., conveying roll temperature: (T _{G ′ ′ max} ) ° C. The distance between the drawing rolls was 200 mm, and under this temperature condition, the peripheral speed difference between the high speed side and low speed side drawing rolls was 2.5 times.

Continuously to the above-described longitudinal stretching, transverse stretching was performed on the longitudinally stretched film using a tenter-type transverse stretching machine having an inner return clip.
Here, with the inner return type clip, the clip fixed to the drive chain finishes a series of transverse stretching operations, releases the stretched film, circulates through the inside of the tenter device, and turns while being cooled by the cooling device. It returns to the entrance of the tenter apparatus again, and means the clip for the tenter apparatus which holds the film after longitudinal stretching.
Moreover, as a tenter apparatus, what is comprised from a pre-heating part, a transverse stretching part, and a heat setting part from the entrance side of a film was used.
Temperature inside of each part of the tenter device, respectively, _"as a reference _max a (° C.), the preheating _{section: (T G" T G} of the resin composition used for evaluation max +20) ° C., stretched _{portion: (T G "max} The temperature was +30) ° C., and the heat setting part was: (T _{G ′ ′ max} +10) ° C.
Under the conditions described above, the film was stretched 2.5 times by transverse stretching to obtain a biaxially stretched film with an average thickness of 40 microns.

  The following evaluation (5-1) and the following evaluation (5-2) were performed as film stretchability evaluation in order to obtain a biaxially stretched film by longitudinally stretching and transversely stretching the unstretched film.

<Evaluation (5-1)>
The longitudinally drawn film which passed through the longitudinal drawing process in the stage before preparing the biaxially drawn film by transverse drawing was sampled for 1000 mm in length, and the dispersion of the thickness in the longitudinal direction was evaluated.
Specifically, with respect to the sampled longitudinally stretched film, first, a portion of 50 mm from both widthwise end portions is trimmed, and from the film after trimming, a strip-like film having a length in the width direction of 50 mm and a length in the longitudinal direction of 1000 mm Were cut out, and the thickness in the longitudinal direction of this strip-like film was continuously measured using a continuous thickness gauge (manufactured by Anritsu). And the average (micrometer) of the thickness measured continuously was calculated | required.
And the ratio (Dmax / Dmin) with respect to the minimum thickness (Dmin) of the largest thickness (Dmax) among the measured thickness was calculated, and the dispersion | variation in the thickness of the longitudinal direction of the longitudinally stretched film was evaluated. The larger the ratio (Dmax / Dmin), the larger the variation.

<Evaluation (5-2)>
The stretching stability in the transverse stretching step in the step of preparing a biaxially stretched film by transverse stretching was evaluated.
Specifically, by using a cooling device attached to the tenter, the clip temperature before traveling in the tenter at the time of transverse drawing with a tenter is ( _TG'max- 40) ° C of the resin composition used for evaluation. Horizontal stretching was continued for 3 hours at four temperatures, varying in steps of 20 ° C., up to (T _{G ′ ′ max} +20) ° C.
Then, according to the quality of the obtained film, “◎” is a case where stable lateral stretching can be continued without causing a defect phenomenon such as breakage of the film at any of the four temperatures. If, only at a temperature of (T _{G ′ ′ max} −40) ° C. among the four temperatures, the film could be broken near the clip and stable lateral stretching could be continued at other temperatures. “〜” And “○” when stable lateral stretching can be continued at other temperatures only by causing film breakage in the vicinity of the clip at only one of the four temperatures. The case where a film break in the vicinity of the clip occurred at two or more of the four temperatures was evaluated as "x".
The clip temperature during traveling was measured using a radiation thermometer. At that time, the radiation thermometer was used for temperature measurement, with the emissivity being made to coincide with the temperature measured by the contact thermometer in a state where the clip equipped with the radiation thermometer was stopped. In addition, in order to enhance the measurement accuracy, temperature measurement was performed after applying black spray or black heat-resistant tape to the surface of the clip.

The polymerization conversion rate was measured by the following method.
A part of the polymerization solution in Examples and Comparative Examples is collected, and the amount of monomer remaining in this polymerization solution sample is dissolved in chloroform to prepare a 5 mass% solution, and n is used as an internal standard substance. -Add decane, measure the concentration of monomers remaining in the sample using gas chromatography (GC-2010 manufactured by Shimadzu Corporation), and calculate the total mass (a) of monomers remaining in the polymerization solution I asked. Then, from this total mass (a) and the total mass (b) of the monomers added up to the time when the sample was taken, the polymerization conversion rate (%) is calculated according to the formula (ba) / b × 100. Calculated.

[material]
It shows below about the raw material used in the Example and comparative example which are mentioned later.
[[Monomer]]
Methyl methacrylate: manufactured by Asahi Kasei Chemicals Corporation N-phenylmaleimide (phMI): manufactured by Nippon Shokubai Co., Ltd. N-cyclohexyl maleimide (chMI): manufactured by Nippon Shokubai Co., Ltd. methyl 2- (hydroxymethyl) acrylate (MHMA) : Combi Blocks [[Other thermoplastic resin]]
Stylac AS 783 (AS resin (acrylonitrile-styrene resin), manufactured by Asahi Kasei Chemicals Corporation)
[[Antioxidant]]
· Irganox 1010 (manufactured by BASF)
・ Adeka stub PEP36 (made by ADEKA)
Adekastab AO-412S (made by ADEKA)
・ Tris (2,4-di-t-butylphenyl) phosphite (manufactured by Wako Pure Chemical Industries, Ltd.)

Example 1
341.0 kg of methyl methacrylate (hereinafter referred to as “MMA”), 39.3 kg of N-phenylmaleimide (hereinafter referred to as “phMI”), 59.7 kg of N-cyclohexylmaleimide (hereinafter referred to as “chMI”), a chain 0.18 kg of transfer agent n-octylmercaptan and 247.0 kg of methyl isobutyl ketone are weighed, added to a 1.25 m ³ reactor equipped with a jacket temperature control device and a stirring blade, and mixed, mixed monomer solution I got
Then, 123.0 kg of metaxylene (hereinafter referred to as mXy) was weighed and added to the tank 1.
Furthermore, 110.0 kg of MMA and 80.0 kg of mXy were weighed into the tank 2 and stirred to obtain an additional monomer solution.
For the contents of the reactor, bubbling with nitrogen is performed at a rate of 30 L / min for 1 hour, and for each of Tank 1 and Tank 2, bubbling with nitrogen is performed at a rate of 10 L / min for 30 minutes to remove dissolved oxygen did.
After that, steam is blown into the jacket to raise the solution temperature in the reactor to 110 ° C., and 0.35 kg of 1,1-di (t-butylperoxy) cyclohexane is dissolved in m × y 4.65 kg while stirring at 50 rpm. The polymerization was started by adding the polymerization initiator solution at a rate of 1 kg / hour, and mXy was added from tank 1 at 30.75 kg / hour for 4 hours.
During the polymerization, the solution temperature in the reactor was controlled at 110 ± 2 ° C. for one hour from the start of polymerization by temperature control with a jacket, and was controlled at 124 ± 2 ° C. for one hour after the start of polymerization.
Then, from 4 hours to 6 hours, a monomer solution containing MMA was added from tank 2 at a rate of 95 kg / hour. Meanwhile, the solution temperature in the reactor during polymerization was controlled at 124 ± 2 ° C.
Furthermore, the initiator solution reduces the addition rate to 0.25 kg / hour 0.5 hour after polymerization start, 0.75 kg / hour 4 hours after, 0.5 kg / hour after 6 hours, and initiator 7 hours after polymerization start The addition of the solution was stopped, and the polymerization was further continued for 3 hours to obtain a polymerization solution containing a methacrylic resin having a ring structural unit in the main chain.
This polymerization solution was supplied to a concentration device consisting of a tubular heat exchanger preheated to 170 ° C. and a vaporization tank to increase the concentration of the polymer contained in the solution to 70% by mass.
The obtained polymerization solution was supplied to a thin film evaporator having a heat transfer area of 0.2 m ² to carry out devolatilization.
At this time, the temperature in the apparatus was 270 ° C., the supply amount was 30 L / hr, the rotation speed was 400 rpm, and the degree of vacuum was 20 Torr. The volatilized polymer was pressurized with a gear pump, pushed from a strand die, water cooled and pelletized. .
Moreover, the weight average molecular weight of the obtained pellet-like methacrylic resin polymer (1) was 159,000, and molecular weight distribution (Mw / Mn) was 2.6.
The obtained methacrylic resin polymer (1) was vacuum dried at 90 ° C. for 5 hours, cooled to 30 ° C. under a nitrogen atmosphere, and used for preparation of a composition.
100 parts by mass of methacrylic resin polymer (1), 0.1 parts by mass of Adekastab PEP 36, 0.05 parts by mass of Irganox 1010, and Adekastab AO-412S using a tumbler type mixer previously substituted with nitrogen A mixture consisting of 0.05 parts by weight was prepared.
Using the dehumidified air whose dew point was adjusted to -30.degree. C. and temperature to 80.degree. C., the above mixture was supplied to a 58 mm.phi. Vented twin-screw extruder for melt kneading. At that time, a nitrogen introduction line was provided at the lower part of the raw material popper attached to the twin-screw extruder, and nitrogen was introduced into the extruder. When the oxygen concentration under the raw material hopper was measured, it was about 1 volume%.
As the operating conditions, the lower part of the extruder and the die set temperature of 270 ° C., the rotation speed of 200 rpm, the degree of vacuum in the vent part was 200 Torr, and the discharge amount was 20 kg / hour.
The melt-kneaded resin composition is extruded in the form of a strand through a porous die, introduced into a cooling bath filled with cooling water preheated to 50 ° C., solidified by cooling, cut by a cutter, and pelletized composition I got a thing.
10. The composition of the polymer in the obtained pellet-like composition was confirmed to find that structural units derived from each of MMA, phMI, and chMI monomers were 81.3% by mass, 7.9% by mass, and 10.3. It was 8% by mass. The weight average molecular weight was 152,000, T _{tan δmax} was 145 ° C., and _{TG ′ ′ max} was 133 ° C.
The evaluation results of other dynamic viscoelastic properties and the evaluation results of film stretchability are shown in Table 1.

Example 2
450.7 kg of MMA, 39.8 kg of phMI, 59.7 kg of chMI, 450 kg of m-Xy, and 0.41 kg of n-octylmercaptan are weighed and added to a 1.25 m ³ reactor which is previously purged with nitrogen, and these are stirred to obtain a mixed monomer solution I got
The mixed monomer solution was then bubbled with nitrogen at a rate of 100 mL / min for 6 hours to remove dissolved oxygen and raise the temperature to 100 ° C. Then, polymerization was initiated by further adding a polymerization initiator solution in which 0.05 kg of t-butylperoxyisopropyl monocarbonate as a polymerization initiator was dissolved in 0.95 kg of meta-xylene at a rate of 1 kg / hour.
In addition, the solution temperature in a reactor was controlled in 100-105 degreeC in 1 hour from the polymerization start. One hour after the start of polymerization, the solution temperature in the reactor was raised to 124 to 126 ° C., and a polymerization initiator solution in which 0.10 kg of t-butylperoxyisopropyl monocarbonate was dissolved in 1.90 kg of meta-xylene was prepared. The polymerization was continued while adding at a rate of 1 kg / hour.
After 10 hours had elapsed from the start of polymerization, a polymerization solution containing a methacrylic resin having a ring structure in its main chain was obtained.
This polymerization solution was supplied to a concentration device consisting of a tubular heat exchanger preheated to 170 ° C. and a vaporization tank to increase the concentration of the polymer contained in the solution to 70% by mass.
The obtained polymerization solution was supplied to a thin film evaporator having a heat transfer area of 0.2 m ² to carry out devolatilization.
At this time, the temperature in the apparatus was 270 ° C., the supply amount was 30 L / hr, the rotation speed was 400 rpm, and the degree of vacuum was 20 Torr. The volatilized polymer was pressurized with a gear pump, pushed from a strand die, water cooled and pelletized. .
The weight average molecular weight of the obtained pellet-like methacrylic resin polymer (2) was 143,000, and the molecular weight distribution (Mw / Mn) was 2.6.
The obtained methacrylic resin polymer (2) was vacuum dried at 90 ° C. for 5 hours, cooled to 30 ° C. under a nitrogen atmosphere, and used for preparation of a composition.
100 parts by mass of a methacrylic resin polymer (2), 0.1 parts by mass of Adekastab PEP 36, 0.05 parts by mass of Irganox 1010, and Adekastab AO-412S using a tumbler type mixer previously substituted with nitrogen A mixture consisting of 0.05 parts by weight was prepared.
Using the dehumidified air whose dew point was adjusted to -30.degree. C. and temperature to 80.degree. C., the above mixture was supplied to a 58 mm.phi. Vented twin-screw extruder for melt kneading. At that time, a nitrogen introduction line was provided at the lower part of the raw material popper attached to the twin-screw extruder, and nitrogen was introduced into the extruder. When the oxygen concentration under the raw material hopper was measured, it was about 1 volume%.
As the operating conditions, the lower part of the extruder and the die set temperature of 270 ° C., the rotation speed of 200 rpm, the degree of vacuum in the vent part was 200 Torr, and the discharge amount was 20 kg / hour.
The melt-kneaded resin composition is extruded in the form of a strand through a porous die, introduced into a cooling bath filled with cooling water preheated to 50 ° C., solidified by cooling, cut by a cutter, and pelletized composition I got a thing.
10. The composition of the polymer in the obtained pellet-like composition was confirmed to find that structural units derived from each of MMA, phMI, and chMI monomers were 81.3% by mass, 7.9% by mass, and 10.3. It was 8% by mass. The weight average molecular weight was 139,000, the T _{tan δmax} was 145 ° C., and the _{TG ′ ′ max} was 133 ° C.
The evaluation results of other dynamic viscoelastic properties and the evaluation results of film stretchability are shown in Table 1.

[Example 3]
In Example 2, the polymerization solvent used was changed from meta-xylene to methyl isobutyl ketone, and the polymerization initiator was changed from t-butylperoxyisopropyl monocarbonate to 1,1-di (t-butylperoxy) cyclohexane A methacrylic resin polymer (3) was prepared in the same manner as in Example 1 except for the above.
A pellet-like composition was obtained by the same method as Example 2, except that the methacrylic resin polymer (3) was used instead of the methacrylic resin polymer (2).
10. The composition of the polymer in the obtained pellet-like composition was confirmed to find that structural units derived from each of MMA, phMI, and chMI monomers were 81.3% by mass, 7.9% by mass, and 10.3. It was 8% by mass. The weight average molecular weight was 187,000, T _{tan δmax} was 147 ° C., and _{TG ′ ′ max} was 134 ° C.
The evaluation results of other dynamic viscoelastic properties and the evaluation results of film stretchability are shown in Table 1.

Example 4
In Example 1, the amount of MMA used is 503.5 kg, the amount of phMI used is 17.2 kg, the amount of chMI used is 29.5 kg, and t-butylperoxyisopropyl monocarbonate (polymerization initiation Methacrylic resin polymer (the same method as in Example 1 except that the amount of the agent used was changed to 0.49 kg and the amount of the n-octylmercaptan (chain transfer agent) added to 0.35 kg 4) was prepared.
A pellet-like composition was obtained in the same manner as in Example 1 except that the methacrylic resin polymer (4) was used instead of the methacrylic resin polymer (1).
When the composition of the polymer in the obtained pellet-like composition was confirmed, structural units derived from each of MMA, phMI, and chMI monomers were 90.3% by mass, 4.0% by mass, and 5% by mass, respectively. It was 7% by mass. The weight average molecular weight was 151,000, T _{tan δmax} was 133 ° C., and _{TG ′ ′ max} was 121 ° C.
The evaluation results of other dynamic viscoelastic properties and the evaluation results of film stretchability are shown in Table 1.

[Example 5]
A methacryl system is used in the same manner as in Example 1 except that the amount of MMA used is 351.2 kg, the amount of phMI used is 79.6 kg and the amount of chMI used is 119.4 kg A resin polymer (5) was prepared.
A pellet-like composition was obtained in the same manner as in Example 1 except that the methacrylic resin polymer (5) was used instead of the methacrylic resin polymer (1).
The composition of the polymer in the obtained pellet composition was confirmed to find that structural units derived from each of MMA, phMI and chMI monomers were 63.3% by mass, 15.8% by mass and 20. It was 9% by mass. The weight average molecular weight was 121,000, T _{tan δmax} was 161 ° C., and _{TG ′ ′ max} was 149 ° C.
The evaluation results of other dynamic viscoelastic properties and the evaluation results of film stretchability are shown in Table 1.

[Example 6]
In a 30 liter reactor equipped with a stirrer, a temperature sensor, a cooling pipe, and a nitrogen gas introduction pipe, the inside of which was previously replaced with nitrogen, 8 kg of methyl methacrylate, 2 kg of methyl 2- (hydroxymethyl) acrylate, methyl isobutyl ketone 9 kg was charged with 2.0 g of tris (2,4-di-t-butylphenyl) phosphite as a phosphorus-based antioxidant.
Thereafter, while introducing nitrogen gas, the temperature is raised to 100 ° C., 5 g of t-amyl peroxy isononanoate is added as a polymerization initiator to start polymerization, and 10.0 g of t-amyl peroxy isononanoate Solution polymerization is carried out at about 95 to 100 ° C. under reflux while adding a toluene solution containing 2.0 g of n-octylmercaptan and 1 kg of toluene dropwise over 2 hours from 1 hour after the initiation of polymerization, and then 4 The time continued.
In addition, when the polymerization liquid one hour after the polymerization start was sampled and the polymerization conversion ratio was confirmed, it was 36.5%.
To the obtained polymer solution, 30 g of a stearyl phosphate / distearyl phosphate mixture as an organophosphorus compound was added as a cyclization catalyst, and a cyclization condensation reaction was carried out at about 100 to 105 ° C. for 2 hours under reflux. .
Next, the solution containing the obtained copolymer is heated to 240 ° C. by a heater consisting of a multi-tubular heat exchanger, and equipped with a plurality of vent ports and a plurality of side feed ports downstream for devolatilization. The cyclization reaction was allowed to proceed while degassing by introducing into the above-described twin-screw extruder.
In the twin-screw extruder, the obtained copolymer solution was supplied so as to be 2 kg / hour in terms of resin, and the barrel temperature was 260 ° C., the rotation speed was 100 rpm, and the vacuum degree was 10 Torr to 300 Torr.
At that time, from the two side feeds provided in the second half of the twin-screw extruder, an antioxidant (IRGANOX 1010 manufactured by BASF Corp.), a catalyst deactivator (zinc 2-ethylhexylate; manufactured by Nippon Chemical Industrial Co., Ltd.) : Product name: Niconic acid zinc 18%), and AS resin (manufactured by Asahi Kasei Chemicals Co., Ltd., acrylonitrile-styrene resin, product name: Styrac AS783) were introduced.
Antioxidant and catalyst deactivator were both added to the polymer at a feed rate of 4 g / hour. The AS resin was melt-kneaded while being added at a feed rate of 0.22 kg / hr and extruded from a strand die to obtain pellets.
A resin composition (6) containing an antioxidant was prepared in the same manner as in Example 1 using the obtained resin pellets.
When the composition of the resin in the obtained resin pellet was confirmed, the content of the lactone ring structural unit was 28.3% by mass. In addition, about content of a lactone ring structural unit, it calculated | required in accordance with the method as described in Unexamined-Japanese-Patent No. 2007-297620. The weight average molecular weight was 126,000, T _{tan δmax} was 135 ° C., _{TG ′ ′ max} was 122 ° C., and the photoelastic coefficient was 1.5 × 10 ⁻¹² Pa ⁻¹ .
The evaluation results of other dynamic viscoelastic properties and the evaluation results of film stretchability are shown in Table 1.

Comparative Example 1
450.7 kg of MMA, 39.8 kg of N-phMI, 59.7 kg of N-chMI, 0.41 kg of n-octylmercaptan chain transfer agent, and 450 kg of meta-xylene are weighed and added to a 1.25 m ³ reactor previously purged with nitrogen, The mixture was stirred to obtain a mixed monomer solution.
The mixed monomer solution was then bubbled with nitrogen at a rate of 100 mL / min for 6 hours to remove dissolved oxygen and raise the temperature to 124 ° C.
Next, 0.10 kg of t-butylperoxyisopropyl monocarbonate as a polymerization initiator was added, and a polymerization initiator solution in which 0.15 kg of t-butyl peroxyisopropyl monocarbonate was dissolved in 3.85 kg of meta-xylene was added, The polymerization was continued for a further 4 hours by adding at a rate of 1 kg / hour. During the polymerization, the solution temperature in the reactor was controlled in the range of 122 to 126 ° C.
After 10 hours had elapsed from the start of polymerization, a polymerization solution containing a methacrylic resin having a ring structure in its main chain was obtained.
This polymerization solution was supplied to a concentration device consisting of a tubular heat exchanger preheated to 170 ° C. and a vaporization tank to increase the concentration of the polymer contained in the solution to 70% by mass.
The obtained polymerization solution was supplied to a thin film evaporator having a heat transfer area of 0.2 m ² to carry out devolatilization.
At this time, the temperature in the apparatus was 270 ° C., the supply amount was 30 L / hr, the rotation speed was 400 rpm, and the degree of vacuum was 20 Torr. The volatilized polymer was pressurized with a gear pump, extruded from a strand die, water cooled and pelletized. .
The weight average molecular weight of the obtained pellet-like methacrylic resin polymer (1 ′) was 139,000, and the molecular weight distribution (Mw / Mn) was 2.5.
A composition was prepared in the same manner as Example 1, except that the methacrylic resin to be used was changed to 100 parts by mass of the methacrylic resin polymer (1 ′) obtained above.
When the composition of the polymer in the obtained composition was confirmed, structural units derived from each of MMA, phMI, and chMI monomers were 81.3% by mass, 7.9% by mass, and 10.8% by mass, respectively. Met. The weight average molecular weight was 136,000, T _{tan δmax} was 138 ° C., _{TG ′ ′ max} was 130 ° C., and the photoelastic coefficient was 0.2 × 10 ⁻¹² Pa ⁻¹ .
The evaluation results of other dynamic viscoelastic properties and the evaluation results of film stretchability are shown in Table 1.

Comparative Example 2
8 kg of methyl methacrylate, 2 kg of methyl 2- (hydroxymethyl) acrylate, 10 kg of toluene in a 30 liter reactor equipped with a stirrer, a temperature sensor, a cooling pipe, and a nitrogen gas introduction pipe, the inside of which was previously replaced with nitrogen. 2.0 g of tris (2,4-di-t-butylphenyl) phosphite was charged as a phosphorus antioxidant.
Thereafter, while introducing nitrogen gas, the temperature is raised to 100 ° C., 5 g of t-amyl peroxy isononanoate is added as a polymerization initiator to start polymerization, and 10.0 g of t-amyl peroxy isononanoate is added Solution polymerization was carried out at about 105 to 110 ° C. under reflux while adding the toluene solution dropwise, and polymerization was continued for 4 hours.
To the obtained polymer solution, 30 g of a stearyl phosphate / distearyl phosphate mixture as an organophosphorus compound was added as a cyclization catalyst, and a cyclization condensation reaction was performed at about 105 to 110 ° C. for 2 hours under reflux. .
Next, the solution containing the obtained copolymer is heated to 240 ° C. by a heater consisting of a multi-tubular heat exchanger, and equipped with a plurality of vent ports and a plurality of side feed ports downstream for devolatilization. The cyclization reaction was allowed to proceed while degassing by introducing into the above-described twin-screw extruder.
In the twin-screw extruder, the obtained copolymer solution was supplied so as to be 2 kg / hour in terms of resin, and the barrel temperature was 260 ° C., the rotation speed was 100 rpm, and the vacuum degree was 10 Torr to 300 Torr.
At that time, from the two side feeds provided in the second half of the twin-screw extruder, an antioxidant (IRGANOX 1010 manufactured by BASF Corp.), a catalyst deactivator (zinc 2-ethylhexylate; manufactured by Nippon Chemical Industrial Co., Ltd.) : Product name: Niconic acid zinc 18%), and AS resin (manufactured by Asahi Kasei Chemicals Co., Ltd., acrylonitrile-styrene resin, product name: Styrac AS783) were introduced.
Antioxidant and catalyst deactivator were both added to the polymer at a feed rate of 4 g / hour. The AS resin was melt-kneaded while being added at a feed rate of 0.22 kg / hr and extruded from a strand die to obtain pellets.
Using the obtained resin pellets, a resin composition (2 ') containing an antioxidant was prepared in the same manner as in Example 1.
When the composition of the resin in the obtained pellet was confirmed, the content of the lactone ring structural unit was 28.3% by mass. In addition, about content of a lactone ring structural unit, it calculated | required in accordance with the method as described in Unexamined-Japanese-Patent No. 2007-297620. The weight average molecular weight was 133,000, T _{tan δmax} was 135 ° C., _{TG ′ ′ max} was 122 ° C., and the photoelastic coefficient was 1.5 × 10 ⁻¹² Pa ⁻¹ . Other dynamic viscoelasticity characteristics The evaluation results of and the evaluation results of film stretchability are shown in Table 1.

  The methacrylic resin composition of the present invention is excellent in transparency, is excellent in heat resistance and weather resistance, and is highly controlled in its birefringence. , A polarizing plate protective film used for a display such as a plasma display, an organic EL display, a field emission display, and a rear projection television, a liquid crystal such as a retardation plate such as a quarter wavelength plate and a half wavelength plate, and a viewing angle control film Optical compensation films, display front plates, display substrates, lenses, etc., transparent substrates used for solar cells, transparent conductive substrates such as touch panels, etc., optical communication systems, optical switching systems, optical measurement systems Waveguide, lens, lens array, optical fiber, coating material for optical fiber, L D of the lens, to the lens cover and the like can be suitably used.

Claims (7)

At least one selected from the group consisting of a structural unit (X) having a ring structure in the main chain, and the (X) structural unit being a structural unit derived from an N-substituted maleimide monomer, and a lactone ring structural unit It is a methacrylic resin composition containing only one methacrylic resin in its composition,
The temperature (T _{G ′ ′ max} ) at which the maximum value is shown in the temperature dispersion spectrum of loss modulus determined by dynamic viscoelasticity measurement is 120 to 160 ° C.
The minimum value of the loss tangent in the range from the temperature (T _{tan δmax} ) at which the maximum value is shown in the temperature dispersion spectrum of the loss tangent determined by dynamic viscoelasticity measurement to the temperature 50 ° C. higher than the temperature is 0.70 to 1.20. A methacrylic resin composition characterized in that In the range from the temperature (T _{tan δmax} ) at which the maximum value is shown in the temperature dispersion spectrum of the loss tangent to the temperature 50 ° C. higher than the temperature, the minimum value of the loss tangent to the value of the loss tangent 10% higher than the minimum value is The difference in temperature (ΔT) is 12 to 24 ° C.,
The methacrylic resin composition according to claim 1.   The methacrylic resin composition according to claim 1 or 2, wherein the weight average molecular weight (Mw) in terms of polymethyl methacrylate measured by GPC is 120,000 to 260,000.   The (X) structural unit contains a structural unit derived from an N-substituted maleimide monomer, and the content of the structural unit derived from the N-substituted maleimide monomer is 5% based on 100% by mass of the methacrylic resin. The methacrylic resin composition according to any one of claims 1 to 3, which is 40 to 40% by mass.   The said (X) structural unit contains a lactone ring structural unit, Content of the said lactone ring structural unit is 5-40 mass% on the basis of 100 mass% of said methacrylic resin, The any one of Claims 1-3 The methacrylic resin composition according to any one of the preceding claims. The methacrylic resin composition according to any one of claims 1 to 5, wherein the absolute value of the photoelastic coefficient is 2.0 × 10 ^-12 Pa ^-1 or less. The methacrylic resin composition according to claim 6, wherein the absolute value of the photoelastic coefficient is 1.0 ^10-12 Pa- ¹ or less.

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